Iceverge

I'd go plasterboard, service cavity, intello, PIR. At lease then if it gets punctured you can see the damage and fix it. Staples and screw holes don't make any difference really. Better still I'd swap out the PIR between the rafters to dritherm or metac batts or best of all pumped cellulose.

@TerryE has chapter and verse on them on his top blog.

There is a sheet in PHPP advising if additional heating is needed in specific rooms. A certified passivhaus (a controlled standard) should perform as per PHPP. On the other hand "passive house" as an uncontrolled term and offers no guarantees unless you ensure adequate oversight yourself.

I'd probably do some research before engaging a builder as many poor practices prevail in the industry. Often not the fault of builders, but rather misunderstood problems and poorly thought out solutions, too often driven by the commercial interests of material manufacturers. To feel comfortable you'll need a good levels of air-tightness but as you spotted it can lead to problems, even structural ones eventually. Here are two good articles from passive house mag to get started with. https://passivehouseplus.ie/magazine/upgrade/victorian-passive-upgrade https://passivehouseplus.ie/magazine/upgrade/radical-retrofit-transforms-pennines-historic-barn What is the current wall/roof buildup you plan to improve?

@dnoble I'm watching this with interest as we haven't installed any heating in our passive house. We're moving in soon and will play suck it and see with a panel heater or two. Have you tried running a plug in heater continually in a central area for a few days to boost the temperature of the contents and structure to something more comfortable. Turning it on intermittently will only heat the air in the room, but it will return quickly to that of everything else around it once switched off. It takes a lot longer for walls ,furniture etc to heat up than air. Did you do PHPP and if so what was your heating load?

Top stuff. Did the enthalpy/heat exchanger bypass make much difference? Your situation sounds almost identical to ours. We have a 2kw heater running with the MVHR since November. It began at 13 Deg at 94% humidity. It's taken a while but humidity seems to have settled at 65% at 17 Deg. We did get some mold when the temperature rose initially when the humidity was still in the high 80's but that's since disappeared.

@joth Any update on the drying?

I couldn't find it on the ICE database @SteamyTea. I won't bother that chap as our house is nearly finished. I had a look and couldn't find what % of organic carbon matter gets trapped permanently. Where can I find that out? For instance in a crop of hemp grown and processed for insulation I imagine almost all of the carbon would remain out of circulation. What % would that equate to if it was just left to rot? @adamj I was comparing a large window with moveable blinds Vs a window half its size with no shading devices. Apologies for the absolutist tone. I was guesstimating to convey my point.

I had a look on their website but I couldn't find any info about the embodied energybof wood crete other than the usual "eco" and "green" and other platitudes. The total product contains PIR insulation, cement and crucially a concrete core so it will have a worse climate change effect than a timber frame with organic insulation. FWIW I do like the durisol and other woodcrete ICF systems.

Either would would work fine. The house won't every feel warm however unless you get a descent air tightness strategy and all your hard work is null if wind can blow through the insulation. Building joists into the wall and is a tricky detail to get right. Do you have any drawings of this?

How windy has it been recently? Ventilation in you attic will be driven by the weather. If it is a persistent problem you could add a through wall extract fan to help airflow. Maybe with a humidity sensor.

Please read this independent of ecological considerations, habitat loss, species extinction etc. That's an different topic. I considered the Carbon offsetting and have come to the notion that it's bogus and an excuse to continue the status quo. In @SteamyTeas article the $300 million over 3 years spent by Shell is only 0.028% of their revenue per year (2019). $1 out of every $3450 that goes through the company. They don't care, it's literally half of what they spend on ads. Climate change is a result of us digging up coal, oil, gas, peat and burning it. We are considering the idea of carbon sequestration as a way to reverse this but the process involves sucking carbon (CO2) form the atmosphere. Plants and trees and algae etc do this and over their lifespans die and fall to the forest/ocean floor. Some of the carbon they contain gets trapped in the earth but much gets released into the atmosphere again as greenhouse gasses. Left to it's own devices this process would eventually trap all the carbon we have released in the last 300 years into oil coal gas and peat again but it would take millions and millions of years. It's an incredibly inefficient process as only a fraction of the dead living thing gets permanently trapped in the ground and helps to slow climate change. The tree you plant today will only make a useful immediate difference to capturing any carbon if you cut it down and dry store it permanently. If you let it fall and rot on the forest floor only a small fraction gets permanently trapped. That's assuming that the land isn't turned back to farmland in a hundred years and the carbon ploughed out again from the top layers. To this end, purely in terms of capturing carbon, you'd be as well off investing in commercial forestry and finding somewhere to store the lumber (like a house!). There is nothing and I mean absolutely nothing which slows carbon caused climate change more than leaving fossil fuels in the bloody ground! Anything else misses the mark by orders of magnitude. To this end if you really want to build low carbon 1.Keep embedded energy low. Despite what the concrete+oil industry says you don't need energy intensive materials to have a superbly performing house. 2.Don't use oil based products ( ICF and SIPS have plenty). Leave them in the ground. 3.Lock up as much carbon as possible using plant based building materials. You can't control bought in energy, so reduce your use as much as possible. Generate as much onsite via solar as you can and send the excess back to the grid to offset someone else's fossil fuel use. I went off ICF because of the cost. That and ICF is the Dime bar of wall construction when what you want is an Armadillo! The soft bit on the inside! Timber is massively nicer to work with and does away with concrete which creates 99% of the suffering and mess on a build. I chased the walls of ours with a 9" grinder. It is the worst job I've ever done. I'm timber framing the garage myself and enjoying every moment. It was difficult to find a builder comfortable with anything other than cavity walls. The common builders manual is full of pictures like this. I suppose the reality is climate change is a generational thing, I'm mid thirties and I say the right words and believe the problem but I'm probably too selfish and lazy to really do much about it. I didn't really understand the issues and still don't with many. Until I learned to calculate the numbers myself I haven't appreciated how much BS there is put out by manufacturers of various products. There is an absolute sea of it. With the external blind option consider whether you want 1:half a window you can see out all the time or 2:all of a window you can see out half the time. It will cost quadruple, need triple maintenance, and loose twice as much heat. I'd be interested to see where your table comes back when you add a timber frame option to the list along with the sips and the ICF. Jonathan

In that case I'd just use Dritherm 32 fullfill cavity batts or EPS graphite blown beads. You'll end up with a U Value of about 0.3 but it sounds like you've got bigger fish to fry with airtightness and uninsulated floors and walls. Are you removing the joists currently in place to make a new first floor? What level of demolition are you going to have to do on the current house?

Welcome welcome. Don't get hung up on overall insulation values as your heating demand will be very small anyway. If it was me I'd keep it simple and put the EPS in the floor all in the one place, how are you supporting the weight of the walls? Will there be foundations and rising blockwork or a DIY insulated slab?

What is your priority @SuperPav, low cost or maximum insulation?

Hi @AdamJ, Excellent posts. You're well on the route to building an excellent house the way you're thinking. FWIW I started my journey at ICF too and ended up with a wide cavity wall after considering almost everything. (If I was to do it again I'd opt for timberframe) A couple of points I noted from your posts. 0.6W/m2K is probably a bit optimistic for whole window performance including frames. I'd put 0.8 to 1w/m2K probably. Overheating seems to be your prime differentiation for energy use with the different build methods. It can be all but eliminated at design phase. I'll try to summarise. Heat added internally (body heat, cooking, radiators etc) and is either fixed or easily controllable ( assuming you don't do anything silly like install an AGA!) Heat added externally is from the Sun and enters through the windows or soaks through the walls/roof. ( more on this later) Windows transfer the bulk of the sun's energy and this can be limited when we don't want it via external shading. This is easy to do on the south as overhangs or brise soleil just sit there passively and block the high midsummers sun while letting the low winter sun in. East and West is more of an issue as the low morning and evening sun can't be shaded without blocking views. Motorised blinds can take care of this but are expensive and require manual intervention or complex software. @tonyshouse has a great blog and discusses his I think. As mentioned solar glass can be used but the real trick is to limit the size of E-W openings. The wall and especially roof buildups can in certain circumstances cause overheating problems and I think this is what is causing your SIPS house to overheat. There are a few names for it but phase-shift and decrement delay are two of the most correct ( i think! ) . In layman's terms it's the amount of time a change of temperature on one face of a wall/roof takes to be noticed on the other face. A hot roof could be above 60deg in the sun and in a lightweight construction like SIPs will transfer heat to the inner surface quickly as there is not much energy taken up to heat the insulation itself. The inside of your roof will then be radiating heat into your house causing overheating. With a high decrement delay roof, by the time the heat had soaked through to the inside it would be nighttime and the heat flow would have already reversed due to the drop in outside temperature therefore never allowing the interior to be exposed to the extreme summer heat. Decrement Delay should be over 12hrs. More doesn't make any difference. 150mm concrete with external insulation to 400mm concrete with external insulation perform identically in heat protection. Overheating is taken care of in the following ways but they have issues. Its better and cheaper not to have it in the first place. 1. Ventilation - Requires manual intervention, creates a security risk with open window, bugs can get in, noise and dust are issues. Only effective when the outside temperature is less than the internal. Relies on air as the cooling medium and it is pretty lousy at transferring heat. 2. Active cooling via aircon - Extra plant required to be installed although can be relatively cheap and if the unit is correct can be used for efficient heating in winter. Low ability to cool large volumes of air unless very large unit installed. Can be run for free from solar PV as @ProDave said. 3. Active cooling via UFH- Niche idea in the mainsteam althought several buildhubbers have used it to great effect. Effective way of cooling quickly and if you're planning UFH not much cost involved either. Finally there is the heat storage capacity of a house. It is the amount of heat you have to add or take away to alter the temperature of the house internals. A house of high heat storage capacity or specific capacity will take much more energy to heat up the structure and will slow the temperature rise but also slow the temperature fall later on. Having a house of very heavy construction (high specific capacity) will do nothing to remove heat, only dampen its onset and retreat. It will help to level peaks during variable weather but do little during a prolonged heatwave. Remember all the other items in your house like furniture, books, floor coverings etc add to this specific capability too. Low specific capacity is never the primary reason for overheating. TLDR. Solve overheating at the design phase by 1. Adjust window sizes to reduce East and West glazed areas and add shading to the south. 2. Build the walls and roof from a material with high Decrement Delay (Phase Shift) ( woodfiber, cellulose, concrete are examples) 3. Don't get hung up on adding too much mass to the interior. It'll only help buffer heat swings, not solve overheating. 4. Allow for provision to add active cooling via solar PV if you think it's needed. Separately on the carbon issue look up MBC timberframes twinwall package with blown cellulose insulation. It is a good example of low/negative carbon construction but many are available.

Welcome Adam I assume the desire for Net Carbon Zero is an environmental aspiration. It might be worth getting a handle on some figures. Concrete emits about 375kg CO2 per m3. EPS is about 66kg/m3. So assuming a passive standard ICF wall is 200mm eps /150mm concrete/50mm eps thats 0.15m3 concrete/m3 and 0.25m3 eps or about 73kg CO2 per area eternal wall excluding finishes or for 200m2 of wall area about 15 tonnes CO2 emitted all in one big bang at the time of building the house. Compare that to an equivalent twin wall timber frame 300mm cellulose built wall. OSB stores about 1 tonne co2/m2 - 200kg co2 to manafacture = 800kg Net negative co2/m3. Timber is also net negative, about -500kg/m3 Cellulose is also about -80kg/m2 Twin wall construction 10mm OSB 300mm cellulose 7% timber 10mm OSB works out at -16kg/Co2/m2 (OSB) - 22.5kg/CO2/m2 (Cellulose) -10.5kg/CO2/m2 (timber) Total Nett negative 48kg/CO2/M2 or about 10 tonnes of carbon stored in the house for the duration of it lifetime. Total Difference of about 25 tonnes CO2 Next build to passivhaus standards at 170m2 floor area and buy electricity from the grid at about 250gCo2/Kwh run it through a heat pump with an average COP of 3 and your carbon savings from change of construction type would heat your house for 116 years. Thats before you add solar PV, Decarbonise your foundations and roof structures, Consider the lowering carbon intensity of grid generation and consider improvements in heat pumps. The reality is that the concrete house will start the race over a century behind and never catch up.

@Johnnyt Whats the final roof buildup going to be?

You can play with this calculator. I find it tremendous fun, but then again that's just me. https://www.ubakus.com/en/r-value-calculator/? I knocked up @Russell griffiths and @ProDave roofs. Have a look at the Heat Protection page. Its shows much greater heat swings with the lower density insulation of PIR that with denser woodfiber. I'd be interested to know is this a problem in reality? Both have similar U values so should preform well in winter. prodave_roof.pdf Russel_G_roof.pdf

Have you plans to convert the garage to living space at any stage? Your architect will probably do a good job regarding the building regs but it sounds like you need a better person to draw up construction details. Unless they can concisely explain EWI window details etc thank them for their time and get someone else. Ideally someone with passivhaus/low energy experience. If they can't explain it in simple terms they don't understand it. Design wise I'd alter a few things. 1. Move the utility to the garage side and make it bigger. 2. I'd bin the chimney in the extension. If you're desperate for a stove use one of the existing fireplaces. 3. Don't bother with knocking through the back wall of the sitting room. A lot of work and expense for little gain. Keep the hopes up.

Welcome Mark, As mentioned time spent at the design phase is invaluable and I feel your pain in trying to find the right professionals. To oft it seems the case "I've always done it this way" or else you are expected to fund someone's ego trip. Nonetheless with research and care an amateur can achieve a very good quality build as many on here can testify. External insulation is an excellent way of cutting thermal bridges and and I think you're on the right track. The passive house magazine have a guide on it and other topics that I found useful. https://passivehouseplus.ie/magazine/guides/the-ph-guide-to-external-insulation How far down the road of the design process are you? Jonathan

I've had quick scan of your manual. Turn on the enthalpy/exchanger bypass and crank the MVHR to its top setting. With the heating on also you should see results in a day or two.

Can you remove the enthalpy module? I had a similar issue with humidity, in fact one particularly cold morning I was worried we might have a leaking window there was so much condensation after running down the frames. IIRC indoor RH was about 90% and temp 14deg. I put the MVHR from 40% to boost for a couple of days and it made a big difference. The house is now at 16deg at 75% humidity buy feels bone dry. Opening the windows periodically and allowing a complete airchange and closing them again will help as the outside air even at 90%RH once warmed up can absorb much more moisture than the already warmer but saturated air inside. It may not be enough though and you might have to resort to a dehumidifier.

+1 no voids. I drilled trial holes in a awkward spots afterwards to check. Also the DPC we used to close the cavity was bulging up everywhere. They may not be 100% bonded thought so any cores should be done prior to pumping.