1000 passivehouses in Austria – how many Gold and Silver in the UK?

Andy
– fascinating statistics and I take considerable comfort from the fact I'm not alone in designing my own Silver self-build, currently in planning.

It would be great to hear from other 'early adopters' of the standards in a similar position to myself on this forum/thread, not least those who aren't engaged in the building/building design professions but have used the standards as part of the brief to their architect/designer/builder.

Any takers?

Steve

Passive stack can't work when the stack effect is zero, yet buildings need ventilation under all weather conditions. (Windows may not always be open in warm weather.) Fresh air intake rates are related to occupancy, not to stack effect or windspeed. Passive stack was phased out in Norway as new buildings became tighter and approached the requirements of Silver. This was 25 yrs ago.

I am trying to concentrate on overseas experience and what works. Germany's or Denmark's CO2 emissions from buildings are falling, the UK's are rising. Could they be doing things right?

In short I'd expect a house or flat of the insulation levels concerned and fitted with PS to use more energy than one fitted with MVHR or MEV. It was such considerations and many more that led Canada, Germany and Switzerland to require mech. vent. in their low-energy standards.

An advantage of prescriptive standards is that they can be enforced more easily and cheaply. A second is they're less prone to fraud or innocent error. A third is that they're more popular with most users. A survey was once done in Oregon. USA. At the time, the state had allowed either a prescriptive or performance route to compliance for some years. It showed that of housebuilders in the period (two years, I think) who had chosen only to meet the bare minimum requirements in the Building Code:
1. one builder had chosen to do calculations;
2. several 10,000s had selected a pre-calculated solution (five combinations of R-values, glazing areas and orientations and thermal mass) which the state certified would meet the underlying energy performance required by Code.

D.

I'm worried about biomass emissions but enough of that – availability's an even bigger issue as you can't burn and create emissions if none's available. Like fossil fuels, biofuels are tradeable and once it becomes an important energy source and in demand for chemical feedstocks or steelmaking or some other task (post-cheap oil) the price will soar until other (slightly less limited) renewables such as solar or wind or geothermal become worth installing.

The total EU-25 potential for biofuels (i.e., a sustainable output after food production is covered) has been put at 1800 TWh/yr (the UK itself uses roughly 2500 TWh/yr). Most countries are more wooded than the UK. Germany wants to turn most of its biomass resource into liquid fuels because they burn more efficiently and cleanly, are more easily stored and can be used in transport.

David.

If only biomass heating, insulation and ventilation could be easily dealt with by Building Regulations and Passive House, Silver & Gold Standards. It isn't easily covered and most people are unaware how limited the resource is compared; e.g. to the energy flow which maintains the current western European standard of living (western Europe uses energy at a modest rate compared to east ern Europe, Russia, the Americas and Australasia).

The sustainable biofuel potential of 1800 TWh/yr quoted for the EU is 30% less than UK national energy use alone. It equals 450 kWh/yr per EU citizen. That's an average 50 watts, or less than the heat loss through the insulation of a typical DHW tank!

As I said, biomass will also be in demand, along with diminishing oil and gas, to make fuel for cars/lorries (maybe “essential uses” only by then), make steel, make fertilisers (i.e., if organic agriculture isn't enough to feed a world of 9 billion people). Given the 2nd. law of thermodynamics, as we move towards an era of extreme energy scarcity it's not a good idea to burn 1 kWh of what will be scarce, high-grade fuel to produce 0.5-0.75 kWh of low-grade heat.

David.

CEPHEUS was a set of mixed (in all senses) projects in Sweden, Germany, Austria, Switzerland & France. UK was set to take part with three projects of 6-10 houses each but could get no matched funding – some things don't change! A 30 yr payback period usually reflects prototype technology or failure to value-engineer projects. It's been empirically lower with German Passive Houses since 2000, the mortgage payments on the extra cost are less than the fuel savings, which is why the number is growing quite fast.

If even a standard Passive House approach can cut the residual heat load of a c100 m2 house to 150 kWh/month (i.e., the load net of active solar hot water) what's the seasonal efficiency of solid fuel plant? At that load, the start-stop losses even of some condensing oil boilers cause a loss of efficiency (recent Danish work).

The conditions in western England, Wales and Ireland give more scope than in Germany (same latitude) to displace fossil fuel by passive solar (larger than normal south windows). The saving could be >500 kWh/yr on a small dwelling and is cheap or almost free if implemented at design stage. Result: residual load maybe <100 kWh/month. What's the efficiency of wood pellet plant at this load (I won't even ask about other wood-burning plant)?

Meet this load from electric heat pumps? A severe peak load problem if a lot of people were all to do it, as my paper on the GEI pointed out.

Active solar backed up with a fluid biofuel that burns as cleanly as/cleaner than LPG? Wadenswil project in Switzerland used this 17 years ago (i.e., LPG, not liquid biofuels) on the four houses with long-term solar heat stores.

Active solar combined with liquid-biofuelled micro-CHP? Seems worth thinking about; produces peak electricity to suit the national grid, no peak load problem since the fuel is stored locally. LPG-fired mini-CHP (6 houses) was used on the other six houses at Wadenswil.

I'm also rural, 5 km fron the nearest gas main. My neighbours burn oil/LPG so the air in this hamlet is strikingly clear compared to past rural air containing more solid fuel combustion products …. but I digress. The even more rural house I'm building will be as close to all-solar as I can get and the logical position to take re. a prototype is for someone else (or me?) then to improve on it.

Incidentally this thread now includes numerous different topics including costs, supply air windows, PSV and the approach to biomass heating systems but I hope this one is clear.

David.

Mark

It was reported a few years ago that the share of construction systems in German Passive Houses to date had been:

60-65% masonry (normal in Germany)
20-25% concrete (BECO and similar)
15% timber

I think this includes detached and row houses and flats and offices might have a higher proportion of heavyweight construction. PHI advice is to use a high thermal capacity, to reduce the need for artificial cooling.

95% of normal German construction is masonry with concrete floors. So both of the less usual materials have a higher share.

In short I see little obstacle to building from masonry, concrete or timber but concrete would be the easiest to get airtight as concrete walls tend to be relatively airtight without a special effort. Timber can give difficulty in detailing and specifying the right membranes; masonry with timber upper floors gives difficulty due to air leaks around the joists (or joist hangers) and concrete upper floors are much easier to make airtight (rest of Europe adopted them 50-100 yrs ago; Ireland is moving in this direction, the UK much more slowly) .

Cavity walls seem a bit OTT, and more difficult to ensure really good workmanship; see elsewhere on this forum. They made sense in the past but solid walls with external insulation are much easier to detail and build. The UK, Ireland & Denmark all use cavity walls so any development of use to one of these will help the other two countries.

LPG fired mini-CHP (or in future, fired by a clean biofuel; i.e. a liquid or a gas) is just my suggestion as to what could make sense outside the gas supply area but where the housing density is still OK for heat mains. One would still expect most heat in spring/summer/autumn to be from solar but this could complement it.

Many lenders in the USA offer lower interest rates for energy-efficient housing – also in Canada – but I've never heard of anything like it in the UK! Certainly AECB hasn't been approached. The Norwich and Peterborough B S might be interested if/when we have time to approach them as they give a small prize every year to an eco self-builder.

David.

Yes, but good as the EBS is it may not always manage the lowest rate on the high street. If the best rate on offer anywhere is 5 percent and an energy- efficient house obtains a reduction of 0.25-0.5 percent this could transform the situation because the monthly repayments on a loan of £105,000 are then the lower than the repayments on a normal loan of say £100.

I think Austria is similar to Germany with regional variations and more timber construction in some provinces than others.

D.

This is not advice – just to get me out of any trouble!

The mortgage market in the UK is ultra-competitive, which means certainly for mainstream lenders that if they can offer very low rates they already do so and don't happen to have a tranche of cheap money lying around on the back of which they can offer even cheaper rates to PassivHaus homes.

The reality is that major lenders in the UK, wedded to volume and fast transaction times, do not believe that there is the demand for a 'green' mortgage. They also do not believe that energy efficiency is an important consideration to home buyers, partly because energy bills are not their greatest outgoing, but also because they are more focussed on location, kitchen, bathroom, Big Brother et al. They don't believe valuers understand green homes etc. Pretty much the position outlined by a major lender yesterday evening at the House of Commons.

There are discounts for energy-efficiency in other international markets, some work better than others, market conditions are very different from the UK, often the discounts are on the back of poor standard lending rates so the discount doesn't deliver that much. In the US the energy-efficiency mortgages are delivered on the back of guarantee schemes usually provided by government bodies – a type of support for lenders which just doesn't exist here.

Think about it – if PassivHaus/green homes are the best, shouldn't they deserve the best rates – yes, but it is illogical to assume any lender will be able to guarantee that the rate they offer will always be the best in the market. It's not in their control, and they have to balance this against other variables in their business like the cost to them of the funds they will be lending on.

No names but you might find that some of the lenders offering carbon-offset mortgages actually have higher rates on these products.

Ecology BS doesn't offer headline grabbing rates on the high-street. But although it doesn't play the game of enticing customers through short term deals, although it turns away non-green business, it has still been recognised as 3rd best value building society and 6th best value lender over 10 years in the 2006 What Mortgage Awards.

And this is before our recently announced C-Change 1% discount to support specific energy-efficiency measures and renewables.