Passive House Advantage

Test6699

With all the talk of renewable energy and geothermal etc it seems to cost alot of money to but something which may take years to make its money back.
Why are we not trying to aim for a passive house and reduce our heat bills to very low figures.

Why pay over 20k on geothermal when that could be put into improving the house quality itself.
An air to water heat exchanger used in conjuction with a heat recovery system (perhaps 5-6k) in combination with solar panels and a back boiler would seem to have a very good chance of heating a 3000sq ft house.
Once a house is highly insulated ie passive with very low u values heating bills should be low.

The sei website site has very good ideas on how to make a house passive. Note it recommends things like pellet boilers, solar and Heat recovery systems and says geothermal is nowhere near to essential.


1. Just to clarify how much should a air to water heat exchanger cost to install.(new house c3000 sq ft)

2. With the new regulations boilers need to be circ 90% efficient. How much would it cost to upgrade to a wood pellet boiler(new house)

3. How much would it cost to make the cavity of the exterior walls wider to make the cavity more than 25cm and then fill with insulatin. What is the standard cavity wall width?

RKQ

We are moving towards passive house design. It does take time.
I can't really answer 1. or 2. as you'll have to ring around for quotes.

3. The standard cavity is 100mm wide (uninsulated) with 100mm solid block innner leaf and 100mm external block leaf. Its normal to install 65mm high density foil insulation, leaving a 35 - 40mm wide air gap / clear cavity.

The air gap is important for damp proofing and also has an insulating factor.

Widening the cavity is a good idea, but requires wider wall-ties and foundations. ( Increased costs) A Structural Engineer may be required depending on wall heights etc.

A passive house is more than just insulation. It requires careful design and glazing positioned to maximise solar gain (free heat from the sun). Full height triple glazing on south elevation, two storey design is also better. Bungalows are quite inefficient forms.

Geothermal is the most efficient form of heating available. It is not great under BER system because it is powered by electricity. The production of electricity in Ireland is mainly by fossil fuels and is therefore frowned upon!( I understand other European BER systems look more favourably on Geothermal)

A proper wood pellet system, based on bulk pellets, can also be expensive.

I agree with back boilers to open fires etc and also believe wood burning stoves are very worthwhile. Passive house design is the way forward but we will all have to change alot to achieve it. ( Different construction methods, heat exchangers, thicker insulation etc)

gooner99

RKQ wrote: »

Bungalows are quite inefficient forms.

I disagree,a bungalow can also be easily upgraded to passive standard.In fact one of the only two passive houses in Ireland is a bungalow.I think that it is certified by the passive house institute,or is in the process.Just to point our that I have no interest in his company,other that I am interested in passive houses and hope to build one.Just not sure which build I will choose.Down to price I'm afraid.

Here is a link to that house

http://www.scanhome.ie/passive/pressrelease1.php

The only other house to have a passive house cert is the mosart designed house.

http://www.mosart.ie/Out_of_the_Blue_Demonstration.2177.0.html

There are lots of companies out there claiming to build passive house. i think that they should be advertising "near passive houses" , as passive houses are not that easy to achieve and need to be certified.

RKQ

I disagree Gooner99, Tomas O'Leary of Mosart, has often stated that he believes bungalows are less efficient that two storey houses.

A 3000 sqft bungalow requires 3000sqft of floor insulation and 3000sqft of attic insulation.
A two storey 3000 sqft house requires 1500sqft floor insulation and 1500sqft of attic insulation.
Immediate saving in insulation area! So, you could double insulation thickness, for same cost as standard thickness insulation in bungalow!

Heat rises so keep ground floor warm will result in taking the "chill" out of first floor bedrooms.

Bungalows by their low rectangular shape are less efficient IMO. Longer pipe runs, longer heat recovery pipe runs, etc.

There are a number of European companies that provide passive homes. Try Swedish and German companies or pm for details. ( Passive homes are not rocket science! they use simple principles that work)

topcatcbr

We have covered this before. A bungalow has a greater exposed external surface area than a two storey house of equivilent volume. Heat is primarily lost through the exposed external surface area so it is an advantage to reduce this as much as possible. Generally speaking.

So basicaly what RKQ said.

badolepuddytat

How much a heating system will cost depends on the size, the size depends on the heat load, the heat load depends on many things. If you are going to build a 300sq m passive house the heat load will be less than 4500 kWh/yr (15 kWh/m2/ annum) . Boiler sizing is ususally completed on a reule of thumb, it's a very different rule for a passive house!

Size that first.

You really wouldn't do both pellet and air to water. Personally i would not go down the road of A2W unless i could see a proven high seasonal efficiency and cheap elect prices!

sas

RKQ wrote: »

A 3000 sqft bungalow requires 3000sqft of floor insulation and 3000sqft of attic insulation.
A two storey 3000 sqft house requires 1500sqft floor insulation and 1500sqft of attic insulation.
Immediate saving in insulation area! So, you could double insulation thickness, for same cost as standard thickness insulation in bungalow!

Although I agree with the bungalow versus 2 storey point being made, it's not quite a simple as this in terms of the financials

My thoughts...

Assumptions:
- A 2 storey house is twice as high as a bungalow
- Both buildings described below are perfect squares.
- A storey is 3 metres high (for easy math)


Bungalow:
Area = 100m2
Perimeter = 10m + 10m + 10m + 10m = 40m
External wall area = 40m * 3m = 120 metres squared

2 Storey:
Area = 100m2 (approx)
Perimeter = 7.07m + 7.07m + 7.07m + 7.07m = 28.28 metres
External wall area = 28.28m * 3m * 2 storeys = 169.68 metres squared

So the 2 storey has 41.4% more external wall.

sydthebeat

But sas, youve forgotten the floor and ceiling areas

the bungalow has 120 m2 wall area + 100 m2 ceiling + 100 m2 floor = 320 m2 exposed perimeter area

the 2 storey has 170 m 2 wall area + 50m2 ceiling + 50 m2 floor = 270 m2 exposed perimtere area

therefore the bungalow has 18.5% more exposed surface area.

sas

sydthebeat wrote: »

But sas, youve forgotten the floor and ceiling areas

the bungalow has 120 m2 wall area + 100 m2 ceiling + 100 m2 floor = 320 m2 exposed perimeter area

the 2 storey has 170 m 2 wall area + 50m2 ceiling + 50 m2 floor = 270 m2 exposed perimtere area

therefore the bungalow has 18.5% more exposed surface area.

I quoted external wall, not external surface. I just wanted to add to what had already been posted.

Plus, the most expensive component to upgrade to passive levels based on the pricings I've seen are the external walls. The roof is very cheap assuming you are insulating on the flat. The floor is cheap enough if you copy the mosart approach. Specialist insulated rafts tend to be pricier.

Don't forget the location of course, a two story will be more exposed to wind than a bungalow. A bit of creative siteing and tree planting will also reduce the chilling effect of the wind.

Even better of course is earth sheltered housing.

Test6699

And just to ask again,
1.What would the cost be to install an air to water heat exchanger and Heat Recovery System. ie use the heat from the domestic water tank to heat and ventilate the house air

2. Window quality. Their high U value is an obvious place to improve but upgrading windows seems to be an expensive business. If say standard windows have a u value of 1.9, what kind of cost should there be to reduce the u value to about 1.3. Is it possible by changing the glass itself or would changing the window frame be needed(which is highly expensive). Again this would be for a new house.

gooner99

Could this be the 3rd certified passive house in Ireland?


http://www.german-eco-homes.ie/news.html

muffler

gooner99 wrote: »

Could this be the 3rd certified passive house in Ireland?


http://www.german-eco-homes.ie/news.html

As these houses are unique Im willing to let it sit.

gooner99 could you confirm if you have any connection with this company.

gooner99

Just to confirm I have no connection with the company.I just stumbled accross their website and thought you guys might be interested.I notice that they are not listed on the list of certified passive houses.But I do notice from their website that they will provide you with certification as part of the deal.

http://www.passivhausprojekte.de/projekte.php?search=2

Hector's House

I went to their (German eco homes) open day on a house near Ashbourne and was very impressed - both with the thought put into energy efficiency and the sheer apparent quality of the build. I'd definitely look at using (and no, I have no connection with the company).

sinnerboy

Test6699 wrote: »

And just to ask again,
1.What would the cost be to install an air to water heat exchanger and Heat Recovery System. ie use the heat from the domestic water tank to heat and ventilate the house air

2. Window quality. Their high U value is an obvious place to improve but upgrading windows seems to be an expensive business. If say standard windows have a u value of 1.9, what kind of cost should there be to reduce the u value to about 1.3. Is it possible by changing the glass itself or would changing the window frame be needed(which is highly expensive). Again this would be for a new house.

1. about 6k + 8k .

2. approx + 30 % . frame design matters .