tag:blogger.com,1999:blog-61892965285506388192024-03-05T23:29:14.009+00:00Passivhaus Refurb - the story of the Totnes PassivhausThis blog is about a refurbishment of a 1970s house with a difference: it is one of the first retrofits of a UK building to achieve certified Passivhaus status.
This blog follows our journey to reach this challenging goal.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.comBlogger36125tag:blogger.com,1999:blog-6189296528550638819.post-79397743301206634952013-09-04T21:55:00.001+01:002013-09-04T22:08:57.862+01:00Summer 2013 - has the house kept its cool?I have been asked this question throughout the summer. Last summer was so cold that we were not able to assess how well the building performs in hot weather.<br />
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Unfortunately, we don't have data loggers or similar equipment to provide lots of quantitative data. That said, July was our warmest month with temperatures in the high 20s (Centigrade) and from memory hitting 30C on one or two days. The house remained comfortable thoughout nearly all of that period within internal temperatures between 22C and 25C. We did have one day when the temperature in my home office (which has a PC with two monitors, one of which is quite old and gives off significant heat) reached 27.5C and it did feel a bit too warm. Other rooms in the house felt quite comfortable throughout.<br />
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<b>Our cooling strategy</b><br />
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Site constraints meant that we needed more east and west glazing than one would have in an "ideal" Passivhaus. This meant needing to use external blinds or similar, not an overhang type shading device which is possible on a south facing window because the sun is lower in the sky in morning and evening. So....<br />
<ol>
<li>We chose to fit Internorm windows with integral blinds - see below - this was a solution specific to our local circumstances, as the window is not a true triple glazed window, consisting of a sealed double glazed unit, and internal venetian blind and a third pane on the outside of the blind: 2 + 1. The blind is in a ventilated space. This means that they have a whole window U-value of only 0.93W/m2K, less than would be needed in many parts of the UK. Internorm do a 3 + 1 window, with a lower U-value but it is considerably more expensive, very heavy and they use Krypton, which is best avoided (more expensive/rare and - when it leaks out as it will after about a decade - results in a more greater drop in performance than Argon-filled units. All the windows on solar gain facades have high g-value glazing (60%), so they will capture 20% more heat than typical 50% g-value triple glazed units. This means that remembering to use the blinds is key to keeping the house cool. This can be solved by using automation but this seems like a step too far in complexity in a domestic situation; although perhaps it is a good idea in an office building.</li>
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<li>We have to sliding pation doors, one on the east and on the west facade. These are "traditional" triple glazed. We planned two pegulas to provide seasonal shading on these two quite large glazed components. Unfortunately, we haven't got the pergulas in place yet, so we did get more solar gain than is ideal. I don't know how much impact this is having on the overall summer performance of the building. When I modelled it in the PHPP, it does affect the frequency of overheating and, had the pergulas been completed before this summer's not spell, we might have avoided the slight overheating on a day or two in July.</li>
<li>We do of course open our windows in the summer and I tried to keep the windows closed in the hot portions of the day (to help keep the heat out) and to make sure the windows were open at night. I think that if we were located in London (where night time temperatures don't drop as much), night time flushing would have been much less effective.</li>
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During the warm spell, I experimented with swiching off the MVHR at certain times of the day. Our intake (and exhaust) terminals are on the west facade wall. During the morning, when the west is in shade, I noticed that the MVHR seemed to help to maintain a lower temperature, as it was drawing in cooler air from outside. In the afternoon, it was drawing in warmer air and this possibly caused internal temperatures to warm more than might otherwise been the case. I tried switching off the MVHR in the afternoon but this seemed to make it feel less comfortable in the afternoon. I think that the reduced air change rate may have resulted in higher internal relative humidity levels, adding to thermal discomfort.<br />
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More generally, we have noticed that the house is more sensitive to internal heat loads than a typical UK home. Some of this is modelled in the PHPP but, in real world use, occupants may bring older electrical equipment, which will add to overheating risk. In my case, the old computer screen does give off significant heat and, although it is smaller than the newer one, uses more electricity. I don't think, however, that it makes economic or ecological sense to replace a perfectly good computer monitor. <br />
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<b>Lessons learnt from this summer</b><br />
<ol>
<li>Keep the MVHR running. Although it provides no cooling function (a common misconception amongst some Passivhaus sceptics), the regular air changes it delivers moderates internal relative humidity.</li>
<li>Use the blinds.</li>
<li>Consider the impact of internal gains - heat emitting devices will have a surprising impact. </li>
</ol>
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<ol>
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Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-69889705118024145182013-02-22T10:16:00.000+00:002013-02-22T10:41:32.596+00:00Totnes Passivhaus at Ecobuild<span style="font-size: x-small;"><span style="font-family: Arial,Helvetica,sans-serif;">Authors of the <a href="http://www.greenbooks.co.uk/passivhaus" target="_blank">Passivhaus Handbook</a>, Janet Cotterell and Adam Dadeby, will be speaking at <a href="http://www.ecobuild.co.uk/visit/venue.html" target="_blank">Ecobuild</a> on 5th March 2013.<br /><br />Slot 1 – first 20 min presentation within 12.30 – 14:00 session – retrofit and new-build case studies – seminar room 1 – “Passivhaus – using Passivhaus to help obtain planning consent … ” see <a href="http://www.ecobuild.co.uk/seminars/session/passivhaus/91/tuesday-05-march/seminar-room-1.html" target="_blank">http://www.ecobuild.co.uk/seminars/session/passivhaus/91/tuesday-05-march/seminar-room-1.html</a><br /><br />Slot 2 – last 20 min presentation within 15.45 – 17:00 session – “Totnes Passivhaus: exemplar retrofit to Certified Passivhaus standard” – seminar room 8 – “Self build and renovation” – see <a href="http://www.ecobuild.co.uk/seminars/session/sustainable-self-build-and-renovation/79/tuesday-05-march/seminar-room-8.html" target="_blank">http://www.ecobuild.co.uk/seminars/session/sustainable-self-build-and-renovation/79/tuesday-05-march/seminar-room-8.html</a> <br /><br />The Passivhaus Handbook will also be for sale at the RIBA Bookshop stand - S1230 and S1330 in the South Hall of Excel.</span></span>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com1tag:blogger.com,1999:blog-6189296528550638819.post-78514886533727406532012-10-24T23:40:00.002+01:002013-01-16T14:12:01.364+00:00The Passivhaus HandbookThe Passivhaus Handbook, A practical guide to constructing and retrofitting buildings for ultra-high energy performance is published tomorrow (25 October 2012). The book expands on the topics discussed in this blog.<br />
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The Passivhaus Handbook has been getting good reviews:<br />
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<i><span style="color: navy;">‘Passivhaus construction looks like
becoming not just popular in the UK, but commonplace. This is a
no-nonsense and engaging introduction on how to do it.’</span></i><br />
<b>Kevin <span data-scayt_word="McCloud" data-scaytid="2">McCloud</span>, presenter of Channel <span data-scayt_word="4′s" data-scaytid="3">4′s</span> Grand Designs</b><br />
<br />
<i><span style="color: navy;">‘This book gives a wonderful
overview of Passivhaus in the UK today, not only enabling interested
parties to understand the principles and pitfalls for their own
projects, but also for policy makers and planning officers to understand
how to avoid some of their ‘own goals’ in attempting to encourage
conservation.’</span></i><br />
<b>Peter Warm, Passivhaus Certifier, WARM Low Energy Building Practice</b><br />
<br />
<i><span style="color: navy;">‘I have now recommended your
book to our four individual current Passivhaus clients wanting to build a
Passivhaus. Your book will save me hours and hours of having to explain
the principles of what we are trying do, to first time clients on a
steep PH learning curve.’</span></i><br />
<b>Andrew Yeats <span data-scayt_word="CEPH" data-scaytid="4">CEPH</span> Architect, Eco Arc Architects</b><br />
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<i><span style="color: navy;">‘I’m delighted to see everything about Passivhaus and its application in the UK collated for the first <span data-scayt_word="tiime" data-scaytid="5">tiime</span>, in The Passivhaus Handbook. The first-hand experience of the authors provides an excellent grounding for the book.’</span></i><br />
<b>Jon <span data-scayt_word="Bootland" data-scaytid="6">Bootland</span>, Chief Executive, Passivhaus Trust</b> <br />
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Here is the description of the book from the <a href="http://www.greenbooks.co.uk/Book/426/Passivhaus-Handbook.html" target="_blank">Green Books website</a>:<br />
<blockquote class="tr_bq">
<br />
The Passivhaus Handbook is an essential guide for everyone wanting to realise a supremely comfortable, healthy and durable home with exceptionally low energy costs. Whether you are building an extension, retrofitting your house or starting from scratch; are new to low-energy design or already have some experience, this book will help you navigate around the potential pitfalls and misconceptions. It brings together current thinking and best practice.<br />
<br />
Passivhaus design focuses first on getting the building fabric right, to achieve ultra-low energy consumption in the most cost-effective manner. The approach is relevant to a wide range of building types and climates, not just to special structures. Passivhaus methodology can be combined with elements of other building standards, such as the UK’s Code for Sustainable Homes, or with other goals, such as a commitment to use low-impact and natural building materials.<br />
<br />
This book includes:<br />
<br />
<ul>
<li>A clear explanation of the underlying building physics.</li>
<li>Detailed information on key elements: avoiding air leakiness, designing out thermal (cold) bridges, moisture management and ventilation strategy.</li>
<li>Tips for creating a cooperative, motivated project team.</li>
<li>Photographs and diagrams throughout.</li>
</ul>
<br />
With steeply rising energy prices, uncertain climatic changes and straitened economic times, the Passivhaus approach, proven over 20 years, offers a timely and practical response.</blockquote>
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The Passivhaus Handbook is available from <a href="http://www.passivhausstore.co.uk/passivhaus-handbook.html" target="_blank">Passivhaus Store</a> as well as from online retailers. I hope you find it useful.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com1tag:blogger.com,1999:blog-6189296528550638819.post-18239577244602040162011-10-23T19:44:00.000+01:002011-10-23T19:51:32.837+01:00We get our Passivhaus CertificationThis week we had a little ceremony to mark getting our formal Passivhaus Certification. Rob Hopkins, of the <a href="http://www.transitionnetwork.org/">Transition Network</a>, kindly came to handover our newly gained certificate.<br />
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We have now been in the house just over two months and we are "looking forward" to a decent winter, to give the house a bit of a test. We are probably going to want to make some adjustments to our ventilation, once we have started using it to transport the small amounts of heat around the house. More on this in a future post.<br />
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From left to right: Janet Cotterell - <a href="http://www.passivhaushomes.co.uk/janet-cotterell.html">Passivhaus architect</a>, <a href="http://www.passivhaushomes.co.uk/adam-dadeby.html">me - Passivhaus energy modelling (and client)</a>, <a href="http://www.passivhaushomes.co.uk/jonathan-williams.html">Jonathan Williams - Passivhaus builder</a>, <a href="http://www.passivhaushomes.co.uk/team.html">Joe Bellows - one of the Passivhaus contractor team</a>, <a href="http://www.passivhaushomes.co.uk/warm.html">Peter Warm - Passivhaus Certifier</a>. <br />
<br />Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com9tag:blogger.com,1999:blog-6189296528550638819.post-4973122985565029102011-09-28T11:53:00.000+01:002011-09-28T11:53:49.850+01:00Living in a Passivhaus, the first few weeksWe have been living in the completed Passivhaus Home since 19 August and are really looking to seeing how the house will perform this winter. So far, the temperature internally has been pretty constant. The only time we had some overheating was over the weekend of 10th and 11th September, when we took part in the Open House event. We had over 150 people visiting and there were a lot of people in the house adding to the heat gain noticeably. It was warm, humid and windy outside (unusual weather) and we found that the tilt and turn windows, some of which we had tilted open to provide extra ventilation and cooling kept blowing closed in the wind.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOHYg7y4ZX3-dG5xKEgyX_DpnpnEYHJe7LmkCOFszPLH_Nxcyl6yLZx036_EO1QDRRar8ITtQaWXRh0qfkkaDUHMXWpUXz9HBFstikNoTIsxXG1KrE_ZwXbTM97sUiVQHWx-az7z-C1r4/s1600/MVHR+heat+recovery+bypass+settings.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="249" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgOHYg7y4ZX3-dG5xKEgyX_DpnpnEYHJe7LmkCOFszPLH_Nxcyl6yLZx036_EO1QDRRar8ITtQaWXRh0qfkkaDUHMXWpUXz9HBFstikNoTIsxXG1KrE_ZwXbTM97sUiVQHWx-az7z-C1r4/s320/MVHR+heat+recovery+bypass+settings.JPG" width="320" /></a></div>We are still tweaking the settings on the MVHR unit (heat recovery ventilation unit). The MVHR is designed to recover the heat from the old, outgoing air and give it to the new, incoming air. Of course, during warmer summer weather, this is the last thing you want. So MVHR units are designed not to recover any heat when this is not needed.<br />
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The heat recovery was kicking in when it was not needed. We have tweaked the settings so that it only comes in at 18C (the minimum temperatures allowed) and turns off if the temperature reaches 20C. The picture above, which was taken a few minutes ago, shows that the summer bypass is enabled, which means that it isn't recovering heat - a bit counter intuitive.I must say that the user interface needs a little improvement. There's definitely a little product development work for Paul here. I feel that this is an often ignored part of a product's design. An impatient user might have decided just to switch the unit into standby until the weather got cold enough for the heat recovery to be needed, which would have defeated the purpose of the system. That said, once set up correctly, we shouldn't have to fiddle with this again.<br />
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Our hot water system has an even less user-friendly interface. Although this is not a Passivhaus specific issue. I think Passivhaus buildings need as much thought to go into how easy they are to use as goes into the design and construction of the fabric. Although not a problem for us and probably for other early adopters in the UK, it will have an impact on the way Passivhaus is perceived.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-41777480545993604162011-07-22T11:38:00.001+01:002011-09-28T11:24:24.349+01:00Certification airtightness testNote: since posting this, the completed air test documents show a result of <b>0.2 air changes per hour</b>. <br />
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It's been a while since I've posted during the always-longer-than-the-client-expects period where all the finishing work is completed.<br />
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We have started the process to get Certification as a Passivhaus, using the UK's top certifier and general guru on all things building physics related, Warm Low Energy Practice. Yesterday, Paul Jennings ("doorfanman"), our airtightness consultant completed the official airtightness test and we got:<br />
<br />
<span style="font-size: small;"><b>0.19 air changes per hour!</b></span><br />
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This is a really big improvement on April's test. Partly because I calculated the internal volume more accurately, using Bluebeam, which has a great tool for measuring dimensions, areas etc of PDF plans. Our internal ventilation volume is 442.38m³ and the April test had been based on a rougher calculation of 400m³. Mostly though, the information from the April test helped us to to improve the weak areas.<br />
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It will be interesting to see how durable our result is. We believe we have created an airtightness layer which lasts.<br />
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I had already put up a DIY shelf in one of the rooms before yesterday's test was conducted, which required drilling a few holes into the plaster than forms the airtightness layer in the external walls of the refurbished part of the house. I put some sealant into the holes before inserting raw-plugs. Obviously, I will be aware of the need not to drill holes in the original external walls without thinking about airtightness. In the new build section, where the airtightness layer is beneath a 50mm service void, I will not have to worry nearly as much about affecting airtightness. For this reason, in any new build, I would always want to design in a service void. I think that, in the real world, it stands a much better chance of remaining intact over the design life of the building.<br />
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Next week, our MVHR (heat recovery ventilation unit) will be commissioned. This will involve, amongst other things, calibrating the airflow to each supplied room (and from each extracted room) to:<br />
<br />
a) ensure that there is an appropriate air change rate for the use of the room<br />
b) ensure that sufficient heat is delivered to the rooms (the tiny trickle of heat needed in a Passivhaus is delivered via the supplied air in the ventilation system)<br />
c) ensure that the total rate of air supplied equals the total rate of air extracted. This is important because if the two are not in balance, the MVHR wastes electrical energy and because it results in the house being slightly over or under pressure, it will increase the flow of air through the fabric of the building.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com3tag:blogger.com,1999:blog-6189296528550638819.post-80369850108645721362011-04-06T18:14:00.003+01:002011-04-08T10:14:53.539+01:000.4 air changes per hour!!<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuPI5vagGmRAh48XIpX2f1zIgNj0LVJRsEE_S2EmMdNtXescF_doz4BghLNf7BQDJ2MNVpJYSzlCYAUCdSeNktecp9cK2qVcpE4AFK-nKLMZlZml3rXnbnLJUOz30ckt9kBcDlRbI6qeY/s1600/Airtightness-result-web-P1000583.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiuPI5vagGmRAh48XIpX2f1zIgNj0LVJRsEE_S2EmMdNtXescF_doz4BghLNf7BQDJ2MNVpJYSzlCYAUCdSeNktecp9cK2qVcpE4AFK-nKLMZlZml3rXnbnLJUOz30ckt9kBcDlRbI6qeY/s1600/Airtightness-result-web-P1000583.JPG" /></a></div>Our airtightness test went really well yesterday. The team achieved a fantastic result of just around 0.4 a.c.h., probably a bit lower, based on an internal ventilation volume of 400m3 - all the more impressive as this is the first build of this type they had worked on, and because more than half of the build is retrofitting the original structure.<br />
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We should be able to improve on that figure in the final test needed for Certification, as we were able to identify the relative weak points.<br />
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We spent a little time today working out how much extra time we spent into doing tasks that were necessary to achieve it. Our conclusion was that it was not a significant extra task. However, everyone in our team are really committed to paying attention to protecting the airtightness layer. We have not had to have a formal "Airtightness Champion" trying to watch everyone constantly, in case it was damaged.<br />
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Watch a clip of the airtightness test on YouTube: <a href="http://www.youtube.com/watch?v=nMTLfj4iXec" target="_blank">http://www.youtube.com/watch?v=nMTLfj4iXec</a>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-74722625670130959032011-04-04T17:33:00.002+01:002020-09-04T11:16:54.938+01:00First airtightness test<div class="separator" style="clear: both; text-align: center;"></div>Tomorrow (5th April) is a big day for the project. Paul Jennings from <a href="http://www.linkedin.com/pub/paul-jennings/19/205/771">ALDAS</a>, will be conducting our first airtightness test. We have been preparing for the day by going through the whole building to ensure there are no forgotten gaps or holes.<br />
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All the windows are now in and although there are still snags and issues to be resolved, they all close well enough for the airtightness test. In the refurbished part of the house, the windows are mounted on the ouside of the original walls with the external insulation wrapping around the window frames to minimise the thermal bridging around the window edge. This also minimises the area of window frame, which helps aesthetically and improves the energy performance of the window installation because window frames are generally the poorest performing part of the window. The photo below shows a section of a window with the first of four layers of insulation attached around it.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjK_6llARHuM31Q3z5Rf8d6qZpKGPulO-1ilRYmeiCjIdB8PGcFGdBlyH-L4w_KElFngb7TE_C8vlAf42XUfsstt248oVOkWqGkJNrqVxGXKxzx5mYhJNlLCPD67STDgocQQV3Dvda6XGs/s1600/External+insulation+part+installed+close+up+around+window-P1000494.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjK_6llARHuM31Q3z5Rf8d6qZpKGPulO-1ilRYmeiCjIdB8PGcFGdBlyH-L4w_KElFngb7TE_C8vlAf42XUfsstt248oVOkWqGkJNrqVxGXKxzx5mYhJNlLCPD67STDgocQQV3Dvda6XGs/s640/External+insulation+part+installed+close+up+around+window-P1000494.JPG" width="640" /></a></div><br />
The next photo shows another section of window with all 180mm of phenolic foam in place. The work to cut and attach the insulation was time-consuming and really unpleasant for the team - the stuff makes you really itchy. The job was made more difficult because Kingspan would not supply their product in broad sheets of 100mm and 80mm depths. Instead we had thinner (40mm and 50mm) and smaller area sheets. This meant much more glueing and cutting. We have also had to use more of the fixings than would have been needed with the broader sheets. Thank you Kingspan.<br />
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In the photo below, the airtightness tape is being applied to along the base of the window, forming a seal between the window frame and the previously parged internal window reveal. We probably have not approached this very well, as the process took longer than expected and was very fiddly. Because the parge layer was rougher than is ideal, we felt we needed to use an adhesive primer in addition to the Tescon Profil tape. It was hard to control what then becomes a very sticky combination of materials! We will need to check back with suppliers, Ecological Building Systems, to try to do it better next time.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirSLKCMojdcELV8plxMcU6dAt5yXd9XqLLzGbXbUHPOKxIAEXd74MGxledi-uIxtl_9U9g7Rzt-dMdY2xSj5kjVJGn077DNQbhNm2SlYZuh7C779NJ6rBCPSaG-Spp6HiBUbcxvAT3OWc/s1600/Tescon+airtightness+tape+being+applied+under+WF1-P1000522.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="360" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEirSLKCMojdcELV8plxMcU6dAt5yXd9XqLLzGbXbUHPOKxIAEXd74MGxledi-uIxtl_9U9g7Rzt-dMdY2xSj5kjVJGn077DNQbhNm2SlYZuh7C779NJ6rBCPSaG-Spp6HiBUbcxvAT3OWc/s640/Tescon+airtightness+tape+being+applied+under+WF1-P1000522.JPG" width="640" /></a></div><br />
We have two large service penetrations into the roof: for the soil vent pipe (SVP) and for the flue. We are using a small gas boiler, which modulates down to about 4kW, to provide our winter hot water - solar thermal will deliver the rest - and any residual heating we may need in the coldest weather. As well as an airtightness issue, SVPs and flues create a potential thermal bridges. The flue has a pair of concentric pipes, the inner one to vent exhaust gases and an outer ring to take in air to the boiler for the combustion process. The flue runs through a grommit/Intello, past 350mm of Warmcel, 22mm of Steico wood fibre board and through the Solitex roof underlay. It could therefore, unless insulated around the pipe within the house, be a significant thermal bridge. We are planning to enclose it, and the SVP, which presents similar issues, with sheep's wool insulation within the boxing. The lack of a need for a flue in an electricity based heating system, i.e. a heat pump, makes gas a less attractive option in a Passivhaus. However, I must admit that the extra cost of a heat pump based solution put me off a bit when we were at the design stage. The Passivhaus Institute are keen to encourage manufacturers to develop and sell "compact units". These have about the same footprint as a fridge freezer - so are super space efficient - and combine the MVHR, hot water (DHW) and space heat product functions in a single unit. One, the Compact P made by Danish manufacturer Nilan, has been Certified by the Passivhaus Institute, and is being promoted in the UK. It looks quite promising, however, most combined devices don't deliver the same performance as the "separates" units would. Our MVHR unit is almost twice as electrically efficient as the Nilan Compact P. And I think compact units need to be completely modular in design, so that parts that fail can be replaced independently of the rest of the machine. The other argument in favour of using heat pumps for DHW and space heating is that they will be better in climate/CO2 terms than gas, as the renewables portion of the electricity grid mix grows. I think that in another five or ten years, the balance - and the economics - may well have shifted in favour of heat pumps and I hope compact units.<br />
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We also have two large penetrations for the heat recovery ventilation (MVHR) unit's intake and exhaust ducts. The ducts themselves are 160mm but are wrapped in 125mm of insulation, making the penetrations 410mm each! This photo is from the inside, where the ducts meet the airtightness barrier, which in this part of the building is the internal plasterwork (parge coat). The walls are still to have their finishing layers of plaster, which will encase the grommit, intello and tescon tape. The continuation of the ducts will also have 125mm of insulation right up to the insulated surround of the MVHR unit.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnGJ_Cu82E-dl9J8GsYyA_-6goOTez8xIywK79lb2ltmhZXKVWDIGLe7-loaKa5qkgEZdx_hvqp7GJC90b7ST-Iw0bO9uyF3Dh7CEggWrq8SjXYFH_adLNuAZp6wddwxBkFUPPRCsyGyY/s1600/MVHR+exhaust+intake+ducts+in+west+wall+with+airtightness+interior+view-P1000551.JPG" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="300" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhnGJ_Cu82E-dl9J8GsYyA_-6goOTez8xIywK79lb2ltmhZXKVWDIGLe7-loaKa5qkgEZdx_hvqp7GJC90b7ST-Iw0bO9uyF3Dh7CEggWrq8SjXYFH_adLNuAZp6wddwxBkFUPPRCsyGyY/s400/MVHR+exhaust+intake+ducts+in+west+wall+with+airtightness+interior+view-P1000551.JPG" width="400" /></a></div>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com3tag:blogger.com,1999:blog-6189296528550638819.post-71459436766504699842011-03-09T22:07:00.000+00:002011-03-09T22:07:22.069+00:00Budget and paybackIt is about time I talked about how much all this is costing. So far we have managed to keep close to our estimated budget and schedule. At this point, it is looking like the build costs, excluding VAT and professional fees, will come out at £1500 per m², which, given that we are having a high standard of internal finish (hardwood floors, granite worktop, decent taps and appliances etc) is not unreasonable. If you strip out the Passivhaus elements, it would have costed £1200 per m².<br />
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I think we have learned a lot about how we will approach new Passivhaus builds to bring the cost differential as close to £0 as possible. This is something we are looking at now. For this project, the extra cost will pay for itself easily over the time I hope to be living in the building, especially now that fuel prices are shooting up - very small increases in energy prices have a disproportionate effect in shortening the payback period. There will be many other non-energy benefits for us - better air quality, much more comfort (no cold drafts or 'cold radiant') and less noise from outside, no radiators on the wall taking up valuable space, loads of natural light, cooler summer temperatures - I think all those must be worth something.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-41766500881912465762011-03-09T15:42:00.000+00:002011-03-09T15:42:52.852+00:00Other Passivhaus RefurbsPassivhaus refurbs are like London buses, you wait for ages for one, then suddenly three in a row come along. The other two projects are both part of the Retrofit for the Future scheme.<br />
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First, is the <a href="http://www.greenoctavia.org.uk/">Princedale Road</a> refurbishment of a Victorian Terrace in Holland Park, West London. The building is owned by a social landlord, Octavia Housing. It gained its Passivhaus certification on 1st March from <a href="http://www.peterwarm.co.uk/">Peter Warm</a>, making it officially the UK's first refurbishment to reach the full (15kWh/m2.a; 0.6 ach @+-50pa) Passivhaus standard. It is a fantastic achievement, particularly as the building is a mid terrace in a conservation area, so there were many complex problems to overcome.<br />
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The second project is here in the south west. The client is <a href="http://www.ndh-ltd.co.uk/">North Devon Homes</a> and the project, known as <a href="http://barbrookpassivhaus.wordpress.com/">Barbrook</a>, is currently on site. The site is much more challenging than our one so that, even though they are 'only' going for the <a href="http://passivhausrefurb.blogspot.com/2010/09/new-passivhaus-refurb-standard.html">EnerPHit</a> standard, their project is every bit as challenging. I am looking forward to visiting Barbrook soon.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-13014951787286955682011-02-20T23:06:00.001+00:002020-09-04T11:14:50.409+01:00Forming an airtight wall-ceiling junctionWe have started to create the airtightness layer at various points in the building. In this post, I will describe the sequencing for one of our ceiling-wall junctions. The airtightness layer in this part of the build is formed by plaster on the wall and by Intello vapour barrier on the underside of the roof I-beams.<br />
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Stage 1) The Intello was stapled to the underside of the I-beams. Tescon tape was applied to join up each row of Intello. We also taped over the staples, in case the Intello is stretched and a small gap appears around the staples, although apparently this is not strictly necessary to achieve the Passivhaus 0.6 air changes per hour (ach) target.<br />
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Stage 2) In order to join the plaster to the Intello, we used Contega PV tape - half adhesive backed, half mesh. We had to use Tescon tape to stick the Contega to the Intello, as the Contega adhesive would not stick properly to the Intello. I had a very helpful conversation with Niall Crosson from Ecological Building Systems where he told me that if the Intello is exposed to humidity, it can affect its ability to stick to the Contega. I guess this must be because of the property of the Intello to vary its vapour permeability according to the ambient humidity.<br />
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Stage 3) After the first photo below was taken, an initial parge layer was applied under the Contega. We took care to put a kink along the length of the Tescon tape by pushing it up slightly, to allow for any possible future movement between wall and ceiling.<span id="search" style="visibility: visible;"><em><br />
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</div><div class="separator" style="clear: both; text-align: left;"> Stage 4) Once it had dried, a second layer was applied to encase the mesh and the Contega tape above it. Then battens were screwed through the Intello to the I-beams. The Intello grips the screws and forms an airtight seal around them, which is only compromised if the screw is removed: it is vital therefore not to remove a screw if it has been incorrectly positioned - better to leave it in place. The space above the Intello (i.e. between the I-beams) is to be filled with Warmcel cellulose, so the battens will help the Intello support the weight of the Warmcel and will provide a 25mm service void to the ceiling plasterboard. 25mm is normally too narrow but I didn't want headroom to be reduced any more than is necessary in this attic space.</div><div class="separator" style="clear: both; text-align: left;"><br />
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</div><div class="separator" style="clear: both; text-align: left;">The remainder of the wall will be plastered later, along with the ceiling.</div>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-48158368729178894162011-01-27T15:20:00.001+00:002020-09-04T11:12:11.017+01:00Airtightness around existing floor joists (and along the top of internal walls)The last few weeks has seen tremendous progress on the build and one issue that I wanted to focus on in this post is how we managed airtightness around the ends of the existing floor joists.<br />
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The picture below shows how the floor joists looked before. Normally, the block work would only be plastered above and below the joists, where the finished wall would be visible. In a Passivhaus refurbishment, the plastering needs to run continuously around the joists.<br />
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We had originally intended to keep the plasterwork below, if it was sound enough, but mostly it just fell off with minimal if any encouragement. As discussed in a previous post, water penetration in the cavity, due to poor detailing at the original roof-wall junction, together with some poor choices with the original render and paintwork seemed to have been the cause.<br />
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The issue of how to make airtight joist ends has been covered in this<a href="http://www.youtube.com/watch?v=LwuGuLn2Fhc"> AECB YouTube</a> video. One of the key points they mention is that the approach needs to take account of whether the wall is going to be insulated internally or externally. If a wall is to be internally insulated, there will be a significant temperature drop at the end of the joist, which brings a risk of condensation because the joist end sits within the cold wall. In the film, to avoid this, they have mounted the joists on joist hangers on an internally insulated wall. Steps then need to be taken to achieve airtightness around the joist hangers.<br />
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In our project, the existing house is being insulated on the outside, so the inner leaf of the existing cavity wall will be the same temperature as the inside - i.e. no condensation risk. This has been our approach to achieving airtightness around the joist ends:<br />
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<b>Stage One</b><br />
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Carlite Bonding parging around the joists onto the original concrete block wall or sometimes new built sections of Thermalite block wall:<br />
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The same principle has been applied to a steel girder fabricated with an additional L-shaped piece, welded with the bottom of the L welded to the web of the girder. This means that the profile of the end of the girder is a solid rectangle, like a joist end, rather than an "I" profile, simplifying making it airtight.<br />
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<b>Stage Two</b></div>
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Priming around the joist ends with Pro Clima's Tescon Primer adhesive. This helps to make sure the Tescon tape sticks to the plaster.</div>
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<b>Stage Three</b><br />
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Taping around the joist and girder ends using Pro Clima's Tescon Profil tape.<br />
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<b>Stage Four</b><br />
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Dotting the corners with Pro Clima's Orcon F adhesive. This is a "belt-and-braces" step. We were not absolutely sure that our tape corner junctions would stay completely airtight. We applied dots of Orcon F to be sure! <br />
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<b>Stage Five</b><br />
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Apply Unibond to the Tescon tape to provide a key for the second parge layer (next stage).<br />
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<b>Stage Six</b><br />
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Apply a second parge layer to seal in the Tescon tape. In the picture below, the joist on the left was originally a double joist. We cut short the thinner of the two rather than try to treat the double joist along its length. Obviously, if the double joint were needed for structural reasons, we would not have been able to cut one joist back.<br />
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<b>Dealing with the edge joists</b><br />
The joists run north-south in our build. There was no edge joist on the east side due to the run of the original roof rafters, however the edge joist on the west wall was mounted close up against the wall and there wasn't enough space around the joist ends to parge and tape around them. One option was to wrap the entire length of the joist in Intello Plus membrane, then tape it down above and below the joist. We decided it was more practical to cut out the existing joist, reduce its length a few cm and re-attach it with coach bolts along its length of the west wall. We used resin anchor gel to secure the bolts in the wall but also applied a generous ring of Orcon F around each a penetration to provide a <i>flexible </i>airtight seal (picture below).<br />
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Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com5tag:blogger.com,1999:blog-6189296528550638819.post-35168671543815797792011-01-18T18:15:00.001+00:002011-01-18T18:27:57.376+00:00YouTube video of projectI've uploaded an interview about the project given in December about the project.<br />
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View it here: <a href="http://www.youtube.com/watch?v=EjNbNJ3YgfQ">http://www.youtube.com/watch?v=EjNbNJ3YgfQ</a>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com1tag:blogger.com,1999:blog-6189296528550638819.post-4207672480204179612011-01-17T13:19:00.000+00:002011-01-17T13:19:06.523+00:00Photos from weeks 9 and 10I've uploaded photos of the build - weeks nine and ten - on <a href="http://www.flickr.com/photos/dadeby/">flickr</a>. Our progress was slowed down by the snow, but the team has been trying to catch up since the new year.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-55512530202615504122011-01-02T22:43:00.000+00:002011-01-02T22:43:45.442+00:00Xmas and New Year updateIt's been a while since I posted. The week-long installation of the scaffolding and 'tin hat' (photo below), the freezing weather and the Xmas/New Year break have meant that there is less to report. I feel very pleased that I didn't decide to skimp on getting a full 'tin hat' - I think it would have been very hard to make the progress we did during December without it. The project reached a turning point in December when we stopped removing bits of the existing building and started adding to it. December also saw a large outflow of money as I tied down as much of the spend on materials as possible before VAT goes up to 20% on 4th January. The rise in VAT further shifts the economic balance away from refurbishments in favour of new builds. Given that we have to address our existing housing stock if many of us are not going to faced with "heat or eat" choices in the coming decades, this policy choice of successive Lab-ConDem governments shows that, in practice, they are more concerned with the welfare of corporate big builders' interests than the citizens who elect them.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuHT-WI8JOgjuok5QP3wfYOMZBY0i5v4G2UP57L_RB6FWXZnt2B_UIqtnrxdgY3w82HwXRHhdcJxKrRwV0OH5b3ruwXU3toFw81rQ8bcju2TIpCUxeR7CuuahGmMMnnfN4c-F9h3fLmKA/s1600/View+down+north+west+P1000071-web.jpg" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="225" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhuHT-WI8JOgjuok5QP3wfYOMZBY0i5v4G2UP57L_RB6FWXZnt2B_UIqtnrxdgY3w82HwXRHhdcJxKrRwV0OH5b3ruwXU3toFw81rQ8bcju2TIpCUxeR7CuuahGmMMnnfN4c-F9h3fLmKA/s400/View+down+north+west+P1000071-web.jpg" width="400" /></a></div>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-52649863214029529052010-12-04T17:42:00.001+00:002010-12-04T17:43:07.825+00:00Week 4 endsWindows finally ordered on Wednesday. I managed to get the window spec selectively trimmed using PHPP to test what effect this would have on the building's performance. The PHPP paid for itself many times over just in this one week of 'optimising' the spec.<br />
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Getting to grips with Therm (also after a long struggle). The model of the external floor-wall junction I created, has produced a provisional psi value of 0.15W/mK, lower than the 0.2W/mK estimate I had previously. Putting that more accurate figure has trimmed another 0.5kWh/m2.a off our Annual Heat Demand. Helpful, as it allowed me to trim a bit more off the window spec.<br />
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I have a sense of having achieved quite a bit this week.<br />
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Meanwhile, the scaffolders have been busy by this time next week, the whole house will be shrouded in a tarp and tin weather shield that will protect the existing structure from the rain and provide a working environment for the site operatives more conducive to accurate and quality work. It also much reduces the risk of weather-related project delays. We have been lucky in that we have missed most of the bad weather affecting the rest of the country, although night time temps have dropped to as low as -10C. Even though we have not had much snow, it has not been nice weather to be working outdoors.<br />
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</div>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-30263762988325161952010-11-29T23:44:00.001+00:002010-11-29T23:53:23.231+00:00Week 4 begins ... the latest on windows and on thermal bridges<b>Windows </b><br />
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Week 4 starts and we <b style="color: #e06666;">Still Haven't Placed Our Window Order</b>. The process of placing the order is taking a lot longer than I'd anticipated. I am optimistic that we will be in a position tomorrow, finally, to press the Go button.<br />
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This has all come as surprise to me, as I'd thought naively that we could spend time fine tuning our window spec, then present our carefully worked out window schedule to our helpful, local Internorm distributor who would then be able to process it quickly and simply ... no probs, job done.<br />
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I realise now that we should have sat down and gone through our schedule with the distributor and talked prices and options at least two months ago, despite not having planning permission or completely finalised window dimensions at that stage. The order process is slow because, while it is easy to spec out the windows for their required energy performance, there are so many other variables to consider and requirements to fulfil. One is the thickness of each pane of glass. If the glazed unit is over a certain area, 4mm glass has to become 6mm. For a given width of bead, this means 4mm less space between the panes, which has a significant impact on the U-value of the glazing. None of these are problems in themselves but overcoming them adds to the cost of the windows unnecessarily.<br />
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Better to use slightly less exacting window performance figures in the PHPP. That way, you can order standard products and get a much more cost effective solution. It seems obvious to me now that I am writing this and, in fact, I have used been using conservative figures throughout the PHPP but I think I got carried away by all the exciting "Leading Edge" or best case figures that the different window manufacturers banded about. Assuming your chosen window provider is in the business of manufacturing windows with near Passivhaus performance, the conversation needs to be about what their <i>standard </i>spec is on those windows. It also needs to be about whether window sizes or other variables will make it harder to achieve the energy performance you are planning for in the PHPP.<br />
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Here are my rules of thumb:<br />
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<table border="1" bordercolor="#c0c0c0" cellpadding="2" cellspacing="0"><tbody>
<tr> <td><br />
</td> <td>My "Leading Edge"<br />
Spec Assumptions this time </td> <td>More conservative PHPP<br />
assumptions I will use next time</td> </tr>
<tr> <td>Glazing "g"-value</td> <td>0.6 or 60%</td> <td>0.5 or 50%</td> </tr>
<tr> <td>Glazing U-value</td> <td>0.5W/m2K</td> <td>0.6 or even 0.7W/m2K</td> </tr>
<tr> <td>Frame U-value</td> <td><br />
0.94W/m2K</td> <td>0.94W/m2K</td> </tr>
<tr> <td>Spacer psi-value</td> <td>0.038W/mK</td> <td>0.05 or even 0.1W/mK</td> </tr>
</tbody></table><br />
I got it right with the frame U-value, because I knew that the "leading edge" spec was a lot more expensive than their standard Passivhaus spec. <br />
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These figures aren't set in stone and I'm sure that each year what is considered standard "Passivhaus suitable" spec will improve.<br />
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<b>Thermal bridging</b><br />
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On Thursday, I attended <a href="http://www.carbonlite.org.uk/carbonlite/course_detail.php?cId=6">a one day course</a> on how to use <a href="http://windows.lbl.gov/software/therm/therm.html">Therm</a>, together with a very helpful <a href="http://www.peterwarm.co.uk/resources/downloads/">Excel spreadsheet developed by Peter Warm</a>, to calculate the psi-values of thermally bridged building junctions.<br />
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Therm is not at all intuitive but does have the advantage of being the only free software that can be used to derive a psi value for many types of thermal bridge. Therm can only model in two dimensions and more complex (and very costly) software needed to model certain types of thermal bridge junctions.<br />
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I have been grappling with this for some months but am now finally biting the bullet and getting to grips with Therm, so that we can replace the conservative (I hope) thermal bridge psi-values (0.2W/mK) we have used in the PHPP to quantify the additional heat loss through the floor-wall junctions of the existing house: this type of thermal bridge is unavoidable in a refurb but can be designed out in a new build.<br />
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Likewise, I want to model the junction between the existing house walls and the window jambs (sides), heads (top) and cills.<br />
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Meanwhile, the first insulation is being installed around the base of the walls of the existing building and in the base of the new build side extension.<br />
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We had to buy double quantities of the insulation in half thicknesses because, even though the thicker sizes do exist, the suppliers will only sell them in very large quantities, unsuitable for a project of our scale. I asked our builders to stagger them slightly to reduce possible thermal bridging in the inevitable, if tiny, gaps between each piece. So instead of this...<br />
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As we got around the corner, we started adding a 50mm overlap, like this...<br />
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</div>It means a little bit of extra labour but it is essentially a free way to get the best from the insulation you are using. The images above are of the insulation around the base of the existing building, 2 x 60mm thick, which we are fitting from <a href="http://en.wikipedia.org/wiki/Damp_proofing">DPC</a> level down about 400mm. <br />
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Installing dual layer of Foam Glas, under the toe of the concrete slab, where the weight of the walls of the new build will bear down - Foam Glas can take much heavier loads than other insulation - we are also taking the opportunity of staggering the two layers to minimise unnecessary thermal bridging.<br />
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Later this week, the scaffolders will be here to start setting up the shroud that will cover the building for the next three months while the external wall insulation, the windows and the new roof are put in place.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-88593550745249915242010-11-22T20:37:00.001+00:002010-11-22T20:58:28.211+00:00More photos from Weeks 2 and 3 - a comment on cavity wallsMore photos from the build <a href="http://www.flickr.com/photos/dadeby/sets/72157625322233759/">here</a>. I may add a couple more during this week. The one below (I can't get it to display correctly, sorry) shows the existing cavity wall insulation, which has become saturated due to water penetration from driving rain (we believe). <br />
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<tr><td style="text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzQdE7iHuHK-euQxO63UyNtTpmXYSw-h2Sc1_p68VccfwsLKQAsi01GOxtE286v3ieLDFRTA5eD4GaUEmI0I6FDZuidsQunMBg5uwX0cGwF2-zcFffUqwz2OfVvkRaEKT-_jfqUXemsrA/s1600/Cropped-south-west+ground+floor+corner+of+existing+house.JPG" imageanchor="1" style="margin-left: auto; margin-right: auto;"><img border="0" height="395" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjzQdE7iHuHK-euQxO63UyNtTpmXYSw-h2Sc1_p68VccfwsLKQAsi01GOxtE286v3ieLDFRTA5eD4GaUEmI0I6FDZuidsQunMBg5uwX0cGwF2-zcFffUqwz2OfVvkRaEKT-_jfqUXemsrA/s400/Cropped-south-west+ground+floor+corner+of+existing+house.JPG" width="400" /></a></td></tr>
<tr><td class="tr-caption" style="text-align: center;">Exposed cavity</td></tr>
</tbody></table> We are planning to suck out all the existing insulation with a super powerful, industrial vacuum cleaner. Although the cavity will only be providing a small portion of the total insulative value of the new wall, we want to minimise the risk of gaps, which could allow air movement within the wall. It this happened, the U-value would be <a href="http://www.aecb.net/PDFs/Impact_of_thermal_bypass.pdf">badly compromised</a>. The replacement insulation (<a href="http://www.instafibre.co.uk/downloads/Cavity/BBA-InstaBead.pdf">Instabead Graphite K32</a>) has a significantly lower claimed conductivity value (0.033W/mK) than the rockwool (0.045W/mK).Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-77781368560527488912010-11-20T21:35:00.000+00:002010-11-20T21:35:40.176+00:00Week 2 of the build - "To refurbish or not to refurbish"Week two has been quite eventful. The old windows are out and much progress made in digging trenches for the external insulation and preparing the foundation for the new build element to the side of the house.<br />
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All (I hope) of the shortcomings of the existing building have now been exposed and this week I have found myself questioning why we are bothering to refurb and not demolishing what is left and starting again. If we had chosen to demolish it, we would have been able to do away with many hours of difficult design work. The problems of thermal bridging between the ground floor concrete slab and the structural walls would have gone away in an instant. We wouldn't be paying tens of thousands in VAT, as VAT can be claimed back for new builds.<br />
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Our builder mentioned as an aside that we could have brought in a big machine that, in no time at all, would have crunched up the concrete that makes up so much of the mass of the existing building. We could have sold it for hardcore at £3 or £4 a bag. This is a good point against the pro-refurbishment argument about saving embodied energy, as the energy in the crunched up concrete would still have had a use in the future, if we'd gone down the new build route.<br />
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Despite that, I still strongly believe there is tremendous value in what we are doing. Even if the economics in our case is likely to be marginal, there will be many lessons to be learned from this project for us personally and, I hope, for others for whom refurbishment is the only option.<br />
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We still haven't placed our window order and I am now getting quite nervous about it. Having spent so much time and effort optimising our spend and the work programme, I can see money being wasted because of the delays in finalising the windows.<br />
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During the week a gas leak was discovered and the site was temporarily evacuated until the leak was provisionally patched up. The local gas infrastructure company is coming back early next week to replace all the pipework from the street to the house. The old pipe was completely rusted away and, as soon as it was exposed, began to leak a lot of gas. It amazes me that a house that was built on a green field site 40 years ago could have been connected to the gas grid with pipework that had no chance of lasting. I have to assume that the gas has been slowly seeping through the ground for many years and that our situation is far from uncommon. If that's true, not only have we been building homes that waste energy hugely, the gas grid itself is wasting gas before it even reaches our gas meters.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-10316162009406800062010-11-14T19:30:00.002+00:002010-11-22T20:58:54.069+00:00Week One photosI've uploaded some photos of this week's activity <a href="http://www.flickr.com/photos/dadeby/sets/72157625264932343/">here</a>.<br />
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Removing all the ceilings has underlined what a big task it will be to make airtight all the junctions with the existing ceiling joists on two floors. The plastering will go up around and between the joists with additional work using Pro Clima airtightness products around each joist.<br />
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<div class="separator" style="clear: both; text-align: center;"><a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgZbhw0KN5Zjk6G1EtPCD6blPWanI3_uO5rlfQaZ9wTWHuaTO54PQvw-UQWs8tXNvcgeXtQYvA5Iz6Gb301dNiRJ4o6xepSBeCEDgMjuR3M28lM8XpiJHh5ix5s_s7lbw4Hxsq_KCqUgc/s1600/IMGP2816web.JPG" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="480" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgZbhw0KN5Zjk6G1EtPCD6blPWanI3_uO5rlfQaZ9wTWHuaTO54PQvw-UQWs8tXNvcgeXtQYvA5Iz6Gb301dNiRJ4o6xepSBeCEDgMjuR3M28lM8XpiJHh5ix5s_s7lbw4Hxsq_KCqUgc/s640/IMGP2816web.JPG" width="640" /></a></div>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-50648639758123681582010-11-12T22:20:00.002+00:002010-11-20T21:36:29.834+00:00Week 1 of the buildWe started on site this week after a rapid exit into temporary accommodation following long awaited granting of planning permission. I was determined that we would not delay the project, before the build had even started, by failing to move out in time. We only just made it though!<br />
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The construction team got to work with great alacrity and a building that had been our home three days before very quickly became a building site. All of the wooden stud partition walls are gone, as is all the internal plaster work, which practically came off on its own. Also gone are all the ceilings, all electrical cabling and sockets and all the old kitchen and bathroom fittings. One of the builders found someone to take all of the pine flooring, which he is going to de-nail, re-sand and lay for a small new build in the neighbouring county. Given that it was installed second hand in our house, it will now be getting its third use, which is very satisfying. Still, despite the fact that nearly all the existing structure remains, five or more skips have been filled so far, although the skip company will sort all the contents to separate out any recyclable material.<br />
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The attached garage, which is going to be replaced by a single storey new build, is also gone, except for its concrete floor, which goes next week, together with all the windows. Next week also sees the end of the road for the hideous concrete chimney, an original feature I'm told: I really can't imagine what possessed the architect or builder who specified it back in 1970.<br />
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It is interesting seeing the building reveal its structure. The quality of the original workmanship is no longer hidden. The 70mm of underfloor screed was removed today to allow us to insulate the floor with the minimum of increase in finished floor height. Unfortunately, the ceiling heights are not especially generous and we could not simply add the insulation on top of the existing screed. The original concrete slab is now exposed everywhere and, as expected, it is very rough and uneven and we will need to find a way to create a level, even base to place the insulation onto. As I think I discussed in an earlier post, the floor was one of the hardest-to-treat elements in the design stage. We were not able to design a floor with a U-value of below 0.15W/m2K, not without spending silly money on very exotic forms of insulation. We have managed to compensate for the relatively poor (>0.25W/m2K) floor U-value but it is still essential we get 70 to 80mm of insulation in there to get the building through Passivhaus Certification.<br />
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This week, we have been going through the fiddly process of building up an order for the <a href="http://www.internorm.co.uk/">Internorm </a>windows. We must finalise the order in the next 12 days to avoid risking delaying the project. I had promised myself that we would not cut things so fine with the timing of the window order but this is proving quite hard to achieve. I can see how easy it is to delay progress on a build by taking your eyes off the windows.<br />
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One of our windows consists of a large, undivided, fixed, north-facing, triple glazed unit. If there are no other constraints, it is apparently possible to get a U-value for the glazing (Ug) of 0.5W/m2K without using very rare and expensive Krypton gas. Because UK building regulations require 6mm glass for (for inner and outer panes?) in windows of greater than 1300mm height (?), rather than the usual 4mm glass, we lose precious mm of Argon-filled space between the panes. This constraint means that the glazing can only get a Ug of 0.6W/m2K if we stick with Argon. The PHPP will come into its own again when I use it to check whether de-rating this window's glazing to 0.6 will affect the building's overall performance significantly. It is worth doing, as adding Krypton into this one window adds a few hundred pounds (£££) to its price.<br />
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It has been interesting as the builder works on further rationalising some of our design choices: balancing materials cost (financially and environmentally) with labour costs and simplifying the execution to minimise the risk of error that could create unintended thermal bridging or air tightness issues. We have managed to simplify a couple of the building junction details. As a client, it adds fantastic value to the project to have that second design iteration. However, it is only working because of the excellent communication and mutual respect between builder and architect. The importance of this team working, "common purpose" if you like, between architect, builder and of course client, has been underlined for me again this week.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-50279898968967902682010-10-28T09:54:00.000+01:002010-10-28T09:54:41.327+01:00The planning sagaThese two posts were written before we received planning permission. It would be so tempting to write a rant about the few, mean-spirited people whose intemperate and ill-informed objections made the whole process so stressful and who, by forcing a redesign and delaying the approval process, added thousands to the project's costs. But I won't. Here are two posts written before approval came through.<br />
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18 July<br />
Our property is one of a row of three different units running north-south, within an estate with quite a strong, distinctive architectural style. The roof ridge on all three properties runs north-south. In our original design, we had wanted to rotate our roof to create a 35° south facing roof, optimised for solar hot water and photovoltaic panels and minimising shading in our garden (the house sits on the southern edge of the 550m2 site with a garden that wraps around east, north, west). Although it is not in a conservation area or listed, the planners wanted a design that conforms very closely to the shape of one of the neighbouring properties: this has translated into retention of the north-south ridge line. We will now have a 23° east-west facing roof, matching the current pitch. The change means that the 4kWp solar PV array we are planning will generate 500kWh a year less than it would have done: equivalent to 12.5MWh less over 25 years. It is annoying for us, as it means £21 a month less Feed-in-Tariff income but it is also extraordinary that one arm of the state prioritises subjective aesthetics while another is rightly concerned with replacing our ageing fossil fuel based electricity generating capacity with non-fossil fuel based alternatives. Given that we are losing an unprecedented proportion of our existing generating capacity (30+%) over a decade and that a portion of the rest is based on gas, which has significant security of supply issues, you'd think that all public policy would reflect this imperative.<br />
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27 September<br />
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I write tonight on what I believe and hope to be the eve of a positive decision to approve our revised plans. The planning process has been horrible. We took a big chance by doing so much design work at risk. This being our first Passivhaus project and a refurb, made it very hard for us to do otherwise. The planning system needs urgently to be redesigned to:<br />
<ul><li> make local decision-making less arbitrary - decisions need to be governed by policy and much less by subjective matters of aesthetics</li>
<li>for smaller householder scale projects, which according to Wikipedia make up 60% of all planning applications, the public should be restricted to a form online and on paper where objections can only be made based on specific issues: loss of light, privacy or other amenity; or on other issues that relate to the local planning policy. The "any other comments" box should be small! Our application generated a huge number of words that took time and resources to read, analyse and read.</li>
<li>There needs to be an explicit warning to the public on the comments form that comments or attacks of a personal nature are not acceptable and will count against any point the commenter wishes to make. </li>
<li>The planning process needs to be integrated with the building control process.</li>
<li>Conservation issues seem to hold sway over sustainability issues - this imbalance needs to be addressed urgently</li>
</ul><br />
28 October <br />
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Well, it's now a month later and we have this week <i>finally </i>got our planning permission. I feel relieved but battle weary. It has been very scary having committed so much resource to the project, knowing that I could not be certain that it would actually go ahead.<br />
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We hope we have all our ducks in a row now and can get started very soon.Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-36704174230923156792010-10-14T14:05:00.001+01:002010-10-14T14:47:22.091+01:00What shape of building works bestAt this year's <a href="http://aecb.net/conference2010.php">AECB conference</a> two weeks ago, Peter Warm gave an informative talk on the Passivhaus certification process. One of his PowerPoint slides showed the impact of a building's form on the wall U-values needed to get to the 15kWh/m2.a target.<br />
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By dividing the total "heat loss" area by the "treated floor area", you get a ratio which describes how compact the building form is. The "heat loss" in most cases is, essentially, the sum of the areas of the building footprint (ground floor), roof and external walls; all measurements taken externally. The "treated floor area" or TFA is the usable internal floor area; calculated according to the convention used in Germany (as you would expect, given that the Passivhaus standard originates there). The higher the form factor ratio, the lower the U-values need to be to reach the target.<br />
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Non-compact detached houses, particularly bungalows, score the worst, sometimes with a ratio as high as 5. They need walls with a very low U-value of around 0.05 to get to the 15kWh target. Blocks of flats typically have a ratio of 2 and they only need wall U-values of around 0.15 to reach the Passivhaus target.<br />
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Semi-detached and terraces are somewhere in-between.<br />
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<table border="2" bordercolor="#808080"><tbody>
<tr> <td align="center"><b>Form factor ratio</b></td> <td align="center"><b>Typical wall U-value</b></td> </tr>
<tr> <td align="center">4 < 5</td> <td align="center">0.05</td> </tr>
<tr> <td align="center">3 < 4</td> <td align="center">0.10</td> </tr>
<tr> <td align="center">2 < 3</td> <td align="center">0.15</td> </tr>
</tbody></table><br />
This means that, if you want to build a Passivhaus with reasonably sensibly sized walls (i.e. less than 500mm thick) or using natural materials or at a sensible cost, you really are going to have to pay attention to the shape of your thermal envelope; the building itself can be any shape you want but the "warm" space (contained by the thermal envelope) needs to be compact.<br />
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In our project, our form factor ratio is 2.53 - so I'm feeling quite pleased with myself, even though this was partly by luck.<br />
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In Passivhaus refurbs I think that building form is as least as important as orientation and solar gain, if not more so.<br />
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Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-62518715904195872662010-10-14T13:20:00.000+01:002010-10-14T13:20:44.578+01:00Interesting post on Green Living Blog at Guardian.co.ukThere is a lot of talk about the importance of using low embodied energy materials in construction. In our project, there is an element of new build, as well as the refurbishment of the existing house. As I have noted previously, we found that it was impractical in this project to use natural, low embodied materials exclusively. In particular, constraints of the existing structure have meant that we are using a lot of Phenolic foam to insulate the floor (on top of the concrete slab) and externally on the walls. In the new build element we are mainly using wood-based structural and insulative materials.<br />
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There is an interesting post on the Guardian's Green Living Blog about this. In a study in Scotland, a two bedroomed cottage takes 80 tonnes of CO2e to build, using standard building techniques and materials. If built to building regs energy efficiency levels, this is the equivalent of six years' energy consumption/CO2e emissions living in the cottage. If that cottage were a Passivhaus, and assuming the energy needed to build it was similar to the standard build, it would take 60 years to 'payback' the energy/CO2e. This gives some support to the argument used by natural material proponents that, if you build a very low energy house, the embodied energy in construction becomes proportionately more important in determining the building's lifetime energy consumption. In the post, they have concluded that refurbishing is the best option (compared with either new build or do nothing) because a refurb of the same sized property is only emits 8 tonnes of CO2e.<br />
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Here is a quote from the article. The link to the original is <a href="http://www.guardian.co.uk/environment/green-living-blog/2010/oct/14/carbon-footprint-house">here</a>.<br />
<blockquote>"80 tonnes is a lot – equivalent to five brand-new family cars, about six years of living for the average Brit or 24 economy-class trips to Hong Kong from London. But a house may last for a century or more, so the annual carbon cost is much less – and for all the new-build options, the up-front emissions from construction work were paid back by savings from better energy efficiency in 15–20 years.<br />
However, the winning option was to refurbish the old house, because the carbon investment of doing this was just 8 tonnes <a href="http://www.guardian.co.uk/environment/blog/2010/jun/04/carbon-footprint-definition">CO2e</a>, and even the highest-specification newbuild could not catch up this advantage over the 100-year period. Once cost was taken into account, refurbishment became dramatically the most practical and attractive option, too."</blockquote>Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0tag:blogger.com,1999:blog-6189296528550638819.post-22757198713446366172010-09-24T09:42:00.000+01:002010-09-24T09:42:12.442+01:00Project Update - September 2010We are still awaiting a decision from the planners, although lots of work continues in the interim, there's nothing Passivhaus specific to report on this month. Watch this space...Adam Dadebyhttp://www.blogger.com/profile/03120182387694751072noreply@blogger.com0