As I see it there are three levels of insulation that are relevant here in New Zealand:
1. No or very little insulation. Perhaps a thin layer (less than 10cm) of Pink Batts fibreglass or some sort of blown-in insulation in the ceiling but most likely no underfloor or wall insulation, single pane windows, lots of air gaps in the wooden windows and doors and maybe in the floor as well. This is your typical older New Zealand house which most people are used to, live in and accept as normal. It requires a big source of heat to warm up and to keep warm and even then it will only heat perhaps half of the house. Usually a woodburner or gas heaters ore maybe electric resistance heaters. Once the heater is turned off or the fire goes out, the house gets cold again quickly, within a few hours.
2. Insulated. This would be a house built in the last few years or now. It has insulation in the walls, ceilings and underfloor. It may have single or double glazing. This still needs a large capacity heater but that heater is now capable of heating the whole house and it stays warm for a while after the heating has been turned off. This is probably what we will have once we've insulated our new house.
3. Passivhaus or superinsulated. This is what I aspire to! It's very simple in principle - more insulation, no air leaks, forced heat recovery ventilation. The insulation level is higher than the average new house (at around 20+cm thick for a Passivhaus) which makes it difficult to retrofit this level of insulation to an existing house. Windows are double or triple glazed and moderate in size. A heat recovery ventilation system uses an air-to-air heat exchanger to warm the cold incoming fresh air with the warm outgoing stale air. The payoff is that the house leaks much less heat than the average insulated house and thus only a small heat source is required to keep the whole house comfortable in any weather or climate. Often the people and appliances and sunshine in the house are enough to warm the house and little or no extra heating is required. No need to chop firewood or pay for a big heat pump, no big gas or electricity or firewood costs and no requirement for sunshine to heat the house.
If only every house was built like this!
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Woohoo, glad to hear you know about Passivhaus standard! (I wouldn't call it "Passive House" though because people get confused thinking they know what that means.) At work we are aiming towarding Passivhaus Standard where ever we can - typically though we use 300mm insulation in walls, 400mm in roofs anyway regardless of Passivehaus.
ReplyDeleteIn terms of your renovation, I'd suggest starting from the top and working down - ie insulate the roof first, then the walls, finally, if you get there, the floor. It would also be worth looking into generally improving the air-tightness of the entire building fabric in tandem with any increase in insulation as this in it self will help with keeping heat in. Seems to be some debate in NZ about if air-tightness is appropriate for the climate or not, I think that if the consrtuction is correct it will be, but if the construction has problems increasxed air-tightness could exacerbate the problems! For example if moisture is getting trapped in the wall construction and can't transfer to the outside.
Look forward to seeing how things progress. Feel free to ask me any questions, I will help where I can or point you to any resources I know of that might help.
Cheers, Elrond
Thanks Elrond, I agree with your thoughts but here it's a lot easier and cheaper to insulate the floors than the walls so it will be the roof and the floors first and yes, air tighnness etc. Will write about my plans later.
ReplyDeleteBenjamin
OK, I have changed Passive house to Passivhaus to the advice of my very clever architect friend!
ReplyDeleteBenjamin
Insulating the floor may provide some benefit, however, making the floor airtight will make more of a difference. You won't lose that much heat relatively through your floor unless it lets draughts through. Unless of course the void under the floor has a lot of cross ventilation in which case airtightness and insulation will be of much greater benefit!
ReplyDeleteI always value people who teaches and educates its readers. I think i am at #2
ReplyDeleteWell, it wouldn't be called "superinsulated" for nothing. Taking steps to further insulate, weatherproof, and renovate the house with heating in mind shouldn't be delayed, especially with the danger of collecting a higher energy bill. You're aiming for this level of insulation there, aren't you? Just keep it up and make sure everything is balanced in the equation. Make sure that less energy is used to warm the house, and that the temperature is still be cool enough to keep you guys comfortable.
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