Garald Posted April 13 Posted April 13 This is neither an intro nor an outro. Rather, this is an account that I've given before in a piecemeal fashion. I told the entire story in one go late at night yesterday in a thread, and have decided to share it here for ease of reference. Got into a major renovation project in 2022, never having done any house renovation before - this is the first time I own. Before you call me foolhardy, recall that (a) pretty much anything in the Paris area gets sold needing work, (b) someone who I trusted at the time recommended to me his supposedly genius architect (henceforth called by her initials, EB). EB talked a good talk but seemed to have an iffy grasp of physics. She brought in a general builder who did a bit of everything. At that point I found this forum (thank goodness). People here taught me a great deal. I managed to get EB to accept some input in the choice of insulation materials, though for reasons that were not apparent to myself or the general builder, she absolutely refused to consider insulating from the outside (even though losing m^2 of indoors space in the Paris area means losing lots of money). EB had bizarre prejudices against heat pumps. She also didn't think I should aim at getting anything higher than an energy rating of D (we started out at F), her argument being that D was the average result of a renovation. That was a very strange argument - why not aim at being much better than average? EB had a strange plan on how to install a heat pump. No installer wanted to accept it. I asked for a sketch and posted it here. People were soon ROTFL and explained well why it would be a total disaster. Explained everything firmly and politely to EB, whose already nasty manner became worse. She started asking for more and more money, including for things she hadn't done yet. She also started showing up hours late to meetings, or failed to show up. At some point, she asked for more money than had ever been agreed upon. I made clear things couldn't go on like that, and she just left. The contractor was in a terrible mood but stayed until the end to finish the job. At around that time, I was telling all of the above to a friend, who asked a question that should have been obvious in retrospect: have you checked that she's really an architect? Guess what - it was quite easy to verify that she was not a member of the Order of Architects and hence had no right to call herself one. It took quite a bit more time and effort to verify that she had never had an architecture diploma. Over time, the picture has become clearer: she took classes in interior design in the 90s (but apparently never finished), got an internship in an architecture studio run by one of her lecturers, was an assistant in an architecture project in the late 90s (she made the architects in the project believe that she was an architecture student), then had some sort of job at another architecture studio, then got some sort of cheap master's (Saturdays only) on urban planning in the late 2000s, and set out on her own career as a fake architect. But all of that I learned over time. In 2023, my focus was on finishing the renovation. Did all heat losses computations myself with the help of the trusty Buildhub spreadsheet, and convinced the general builder that old cast iron radiators can work perfectly well with a heat pump running at medium-low temperatures. (When it comes to understanding heat-pumps - many thanks are due both to Buildhub and to Feynman for one of his first-year lectures on physics: if you read it backwards (well, reversing the direction of the arrows), you understand everything.) Got an energy rating of B in 2023. Since then, I've been improving things here and there: while it is my impression that the general builder was reasonably honest and mostly competent, he did some things much better than others. By now, I know a good plumber, a good hardwood person, etc. It is clear that I will have to fix some things that should have been fixed while the renovation was ongoing (e.g., the plumbing in the kitchen is not just malfunctioning but illegal; the plumber implies I should not worry too much about the last bit, as half of the plumbing in Paris is illegal, and the rest is mostly substandard - but of course I'll get it fixed). OK, enough for the human side of the story. Let me summarize where things stand technically, and how I see possible further work in terms of cost/benefit. 2
Garald Posted April 13 Author Posted April 13 Current state of affairs Tests Energy consumption: estimated at 100 kW/m^2/year at the end of the first stage of renovation, in the summer of 2023 (energy rating B for French standards). Airtightness: measured at Q4Pa-surf in m3/(h.m2) : 0,98 in November 2024. I've put into practice all recommendations in the report; the testers say that, if I have done everything correctly, I should now be around 0,7. Insulation My place is most of a townhouse with ground floor, first floor and attic. (Most of the ground floor is not mine - it's a GP's office.) Southern side (south-east-south; street side): insulation from the inside by BioFib Trio, up to code (R>4). Western side (grouchy neighbour's garden): insulation from the inside by BioFib Trio, up to code (R>4). Could hypothetically insulate from the outside some day; would need to get to know said grouchy neighbor. The main reason would be to regain 20cm of space, but it's probably not worth it, even though that's 7*0.2 = 1.4m^2 space to recover. I take it can be insulated from the outside decades from now, once standards rise and insulation decays. Northern side: insulation by a combination of BioFib Trio (5cm) and a reflective insulation with more vegetables on the back. Up to code (R well above 4) if you believe in reflective insulation. Thermal-camera pictures show it's not too bad. Condensation may be a long-term issue, according to Ubakus. Some thermal bridging likely; ground-floor corners very cold. For what it is worth, the general builder says he wanted to insulate from the outside to begin with, but the person he still hasn't accepted is no architect would not let him. Eastern side: most of it is covered by a ghost kitchen next door, but we insulated anyhow (the building next door is low - its roof is lower than my first-floor ceiling), with the same arrangement as the northern side. As a result, the staircase going to the attic is very narrow. Attic: This is the weakest part of the entire insulation. The short sides (murs pignons) are now insulated in the vegetable/reflective/vegetable combination. You can see some of the metal framing with a thermal camera. The bits before the eaves (combles perdues) are now insulated with cellulose. The low walls are disappointingly cold according to the thermal camera, though that may just be a function of how air circulates. I don't think the general builders used any kind of membrane. The worst part is most likely the ceiling. It was the *only* bit that was insulated when I bought the place - the owners before the previous ones got that bit done with fibreglass 15 years ago. That's still there, though bits around the skylights were replaced by rockwool by the general contractor. One can really feel that insulation in the attic is not to the same standard as elsewhere, particularly during the summer. (Outside shades on the skylights have helped a great deal.) Ventilation PIV. Has some sort of radiator going around the input (hidden inside a box), fed by the heat pump. It barely seems to reach the attic (which may be too airtight to begin with; I can open the handlebars in the skylights to let air through, but I can't leave them open - rain would come through and ruin the hardwood). It may ventilate the first floor Green power generation Some solar panels (3kW peak). Could install many more. Plans Short term (a) Fix the plumbing in the kitchen and under the house (there was a leak); the new plumbing under the sinks makes plumbers wince because of its amateurishness, but I suppose I'll let it be for the while being. (b) Get a quote for insulating whichever bits of the heating/hot water pipes can be insulated without ripping things apart (the fake architect was very much against insulating the pipes for whatever reason). (c) If I get a reasonable quote, insulate the attic ceiling properly, with a material with good thermal inertia (either wood fibre or a mixture of wood fibre and cork). Just got two quotes - we are discussing them in a thread. In the long term (>5 years), I can consider: (i) insulating the northern wall from the outside; this is something that needs to be decided by the coop as a whole, but it's a tiny coop - a couple and I are the only ones who ever show up to meetings) and we are all leaning that way. Of course outside appearance will improve, looking from the courtyard (the other building in the coop is not looking great). (ii) if I have money, money, O!, I could 'raise the roof', i.e., recreate the attic as a space in most of which I could actually stand. That would of course involve destroying at least half of the current roof, and probably losing all the money invested in (c) above (companies are loath to reuse insulation material installed by other companies). OTOH it would increase the value of the property a great deal. (Prices around here are determined mainly by the number of m2 in which a 180cm-tall person can stand.) (iii) it's probably best if I consider installing MVHR only if and when I do (ii). One company says it's not worth it right now, but could probably do it for 8k-ish if the attic gets completely rebuilt, as then matters would be simpler. Another company would be ready to install MVHR right now, but for a huge amount (20.5k). This general plan would seem to make sense, though at the same time I don't know how to escape the dilemma between (c) and (ii). The coop will probably be ready to do (i) in about 5 years (we will start setting money aside now). Perhaps (ii) and (iii) should be postponed indefinitely, except that it would make sense to do (ii) at the same time as (i). Oh well. 1
SteamyTea Posted April 13 Posted April 13 On 13/04/2025 at 05:31, Garald said: 100 kW/m^2/year Expand 100 kWh.m-2.year-1
Garald Posted April 13 Author Posted April 13 (edited) On 13/04/2025 at 06:07, SteamyTea said: 100 kWh.m-2.year-1 Expand Ah yes. It's one of those things where you ask yourself 'am I making a standard mistake here?' but it's too early in the morning. Edited April 13 by Garald
SteamyTea Posted April 13 Posted April 13 On 13/04/2025 at 06:19, Garald said: but it's too early in the morning. Expand It is an hour earlier here, but it isn't really as I am 7° West of you.
Garald Posted April 13 Author Posted April 13 Ah, before I forget. There's another possibility for the long term (5-10 years): a Canadian well - could be an option if the coop decides that we'll redo our courtyard (currently concrete, and bearing 90 years' worth of scars). Apparently there's an old, unused septic tank down there. - Could dig that up and use that for a Canadian well instead, no? - I guess Canadian wells should in principle be compatible with both PIV and MVHR? In the current French DPE calculation method (dating from 2021), the instructions for rating a place with a Canadian well are 'rate it as if it had MVHR' - I guess they would consider that someone who has both is overdoing it and deserves no extra points. But at this stage there are more pressing issues. On 13/04/2025 at 06:28, SteamyTea said: It is an hour earlier here, but it isn't really as I am 7° West of you. Expand I was typing in the dark.
ProDave Posted April 13 Posted April 13 On 13/04/2025 at 06:36, Garald said: Ah, before I forget. There's another possibility for the long term (5-10 years): a Canadian well - could be an option if the coop decides that we'll redo our courtyard (currently concrete, and bearing 90 years' worth of scars). Apparently there's an old, unused septic tank down there. - Could dig that up and use that for a Canadian well instead, no? - I guess Canadian wells should in principle be compatible with both PIV and MVHR? Expand This leads onto "What is a Canadian Well?" Care to start yet another thread to enlighten those of us that have not heard of that?
Garald Posted April 13 Author Posted April 13 (edited) On 13/04/2025 at 09:13, ProDave said: This leads onto "What is a Canadian Well?" Care to start yet another thread to enlighten those of us that have not heard of that? Expand Didn't we have a thread on this? Ah yes, both you and I posted on it. It's when incoming air first goes through pipe (lots of it: 30m to 60m is typical) laid fairly deep underground (2m to 6m), thus cooling the air in summer and warming it in winter. Apparently the inside gets coated in silver salts so that it doesn't become a colony for fungi and bacteria: https://www.fiabitat.com/les-precautions-sanitaires/ Also, consult your friendly neighborhood radon map. Edited April 13 by Garald 1
jack Posted April 22 Posted April 22 On 13/04/2025 at 09:21, Garald said: Apparently the inside gets coated in silver salts so that it doesn't become a colony for fungi and bacteria: https://www.fiabitat.com/les-precautions-sanitaires/ Also, consult your friendly neighborhood radon map. Expand Silver salts or not, I'd still be reticent to use something like this unless I could be 100% certain standing water could be avoided. A more energy intensive version is a buried brine loop that feeds a heat exchanger. Needs a pump, but at least there's hydraulic separation.
Garald Posted April 22 Author Posted April 22 (edited) On 22/04/2025 at 09:34, jack said: Silver salts or not, I'd still be reticent to use something like this unless I could be 100% certain standing water could be avoided. A more energy intensive version is a buried brine loop that feeds a heat exchanger. Needs a pump, but at least there's hydraulic separation. Expand I'll try to talk in the next few years to people here who have one installed. (It's a fairly common thing in France among reasonably eco-conscious people.) In my case, it's something to consider doing 5-10 years in the future (or the next time we need to rip up the courtyard, whichever is sooner). I take it's out there in the fruity fringe in the UK? Edited April 22 by Garald
jack Posted April 22 Posted April 22 On 22/04/2025 at 10:03, Garald said: I take it's out there in the fruity fringe in the UK? Expand It's been discussed on BuildHub a few times in the past, but I'm not aware of anyone actually doing it. I think there are genuine fears about the health risks. I'm sure someone (possibly me!) posted a few years ago about that house that had serious issues with such an arrangement. They paid no attention to any of the risks though.
Garald Posted April 22 Author Posted April 22 I get the feeling that here they are standard enough that the basic measures to be taken are agreed upon. https://conseils.xpair.com/consulter_savoir_faire/puits-canadien-ventilation-double-flux/description_puits_canadien.htm#part-1237 Reading a bit more - it seems this is not a possibility for me; the coop simply doesn't have enough land (you need to fit straight 25m-long tubes somewhere; some say 50m are better).
Gone West Posted April 23 Posted April 23 I looked into the possibility of using this type of system for my MVHR in 2010. It was the Rehau AWADUKT, hadn't heard of Canadian Well before. The details don't seem to have changed much in the last fifteen years. https://www.phstore.co.uk/PDF/Rehau/AWADUKT_thermo_urun_programi-data.pdf
JohnMo Posted April 23 Posted April 23 I also looked when we were planning, at the Rehab system, but as our site is pure sand it's a system that cannot get all the benefits when in sand. The install instructions state do not bed pipes in sand, use either clay or soil. 1
jack Posted April 23 Posted April 23 On 22/04/2025 at 21:07, Garald said: I get the feeling that here they are standard enough that the basic measures to be taken are agreed upon. Expand Have they been standard for a long time? I was looking into this in 2014 when we were planning our build (we completed at the end of 2015). I couldn't find much information about them, and most of what I read involved situations where they'd gone wrong. That said, I've never heard them called a "Canadian well" before. Perhaps if I'd known that term I'd have found more useful info! On 23/04/2025 at 08:10, JohnMo said: I also looked when we were planning, at the Rehab system, but as our site is pure sand it's a system that cannot get all the benefits when in sand. The install instructions state do not bed pipes in sand, use either clay or soil. Expand We're on pretty-much pure sand too (our deeds say the plot was bought from a sand and gravel quarry in the 1950s, and there's a lot of that sort of quarrying around me), so it sounds like it wouldn't have worked for us anyway.
SteamyTea Posted April 23 Posted April 23 (edited) On 22/04/2025 at 10:03, Garald said: In my case, it's something to consider doing 5-10 years in the future Expand Why not put a temperature logger into the ground at the depth the pipe will be fitted. That, along with the local air temperature, will give you enough data to make a properly informed decision. Be wary of asking people how a device that costs thousands is performing, they won't want to loose face. Real numbers won't lie to you. (Not so sure about those irrational and imaginary ones, have to ask the Cardinals) Edited April 23 by SteamyTea
Garald Posted April 23 Author Posted April 23 On 23/04/2025 at 09:12, SteamyTea said: Why not put a temperature logger into the ground at the depth the pipe will be fitted. Expand Aha - how do you do that? (Can it be a DIY job?) At any rate, as I said, the plan is shelved now in my case - not enough land.
SteamyTea Posted April 23 Posted April 23 On 23/04/2025 at 09:14, Garald said: how do you do that? (Can it be a DIY job?) Expand Cheap microcontroller, an even cheaper 1Wire temperature sensor and some basic coding, which will be already written for an ESP32 or Raspberry Pi. You would love it, more data than a Spreadsheet can handle.
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now