Grand Designs - 18th Feb

[satans worm]

Tuna said:

cardigankid said:

Yippee! Got the last word.

Didn't

Actually, I'm not really arguing with you either. When we first started planning our house, I was also dead against MHVR, but many of my reasons for not trusting or wanting it (moving parts, cost etc.) were just seen as non-issues by people in Canada and Europe where they're in common use. For our specific build it then emerged that it would give us a lot of benefits that we just couldn't achieve easily otherwise.

Ho hum.

Out of interest Tuna, do you want the MHVR because you like the idea of it or because it is cost effective in the long term, in which case how long is long term?

Edited by satans worm on Friday 20th February 21:36

[cardigankid]

OK then. To explore this further, how are you running the system, off the mains, or from batteries with solar power?

How efficient is the heat recovery system, and is the supply air 100% fresh or to some extent recirculated?

I would be very interested to hear of the other benfits you anticipate from this system, and whether you think that there are any benefits from the airtightness separately, also what is your approach to keeping the duct system clean.

Not saying I want one mind you!

Looking back on More4 at the weekend I saw a repeat of what I reckon is the best looking GD ever (the Captain Mainwaring guy who put on the gullwing timber roof which then got ruined by rain) and the most impressive (the old couple who ordered a Huf House, envelope up in four days, no sign of any kind of upset or issue from start to finish, everything perfect - showed a lot of younger more gung-ho people how it should be done)

[Tuna]

Quick answer - air leakage is the single largest source of heat loss in a house:

* Infiltration / Air Leakage: 35%
* Windows and Doors: 18%-20%
* Floors and Below Grade Space: 15%-18%
* Walls: 12%-14%
* Ceilings: 10%

So over a third of your heating bill goes straight out of the window (or trickle vent!). If you build with walls, roof, windows and floors insulated better than current spec, that gets even worse.

A heat recovery unit can be over 90% efficient, and use only around 100 watts to run. It sucks warm, stale air from the house (usually the bathrooms and kitchen - no more condensation and mould), and blows in fresh air from outside (into the living areas and bedrooms). The incoming air is heated by the outgoing air, so you only loose a fraction of the heat that would normally escape. Filters ensure that the incoming air is clean. There is no re-circulation of air, and the only air being blown into rooms is fresh air from outside.

Then end result should be that you get fresh, clean and warm air in the living areas, and a controlled flow through the house, taking stale air and smells with it.

So, though it will run off mains electricity, the units can produce a saving of 10:1 - for every watt used to run the system, you save ten watts heating your house.

Clean air, no condensation and lower heating bills. That's why we're going with the system.

[scotal]

Stupid question, but are there grease filters in the pipe that goes from the kitchen to the extraction unit?

[dan101smith]

All that time, effort and money to build a house, and they go and stick it in Staplehurst.

As you can see from the pics, it's a pretty secluded location down there. There was one shot where you could see the church in the distance, and no houses in between - that's how secluded it is (bar the couple of houses opposite), so for someone to object to planning on that grounds is a trifle ridiculous.

A friend did some electrical work there, commented that the design really seems to "work" as a family home, more so than you might expect from looking at it.

@JulesV - which pub do you know round there?

[SJobson]

Tuna said:

Quick answer - air leakage is the single largest source of heat loss in a house:

* Infiltration / Air Leakage: 35%
* Windows and Doors: 18%-20%
* Floors and Below Grade Space: 15%-18%
* Walls: 12%-14%
* Ceilings: 10%

What spec windows/doors/floors/walls/ceilings contribute 65% of the loss, though? Considering the other complications involved in building air-tight then having to force ventilate, it might be possible to halve the other losses through better materials but traditional design.

[cardigankid]

Look, I can see the benefit in heat recovery, don't get me wrong. I just have a very sensitive bullst meter, and I sense that the whole airtightness thing is getting out of hand. And I mistrust ducted systems for the reasons given above.