Passivhaus: the future of housing is superinsulated - Political Forum

Slartibartfas · 10-28-2007, 07:25 PM

Ok, I mentioned the Passivhaus concept already a few times here, but I think after we have already a very nice thread over how our primary energy sources might look like (and also our electricity production out of them), we lack a thread about key technologies how we can prevent the need for energy in first place.

As far as it comes to housing the Passivhaus standard developed in Darmstadt, Germany is leading the way. Houses built according to this standard are able to safe 95% of all needed energy in comparision to the average housing that exists currently and 75% in comparision to new regular housings that are not built in a low energy way.

How does it work? There is no magical breathtaking technology involved actually. The wheel has not been invented another time, but for the first time all existing technologies needed have been combined into a single concept:

Super insulation (no heat bridges)
triple isolated window glasses
air tightness of the building
heat recovery from exhaust air in "air to air" heat exchangers
passive preheating of fresh air
southern orientation where possible
hot water supply using renewable sources like solar heating is preferable
energy saving household appliances

The first four aspects are the fundamental ones. The latter ones should be followed when possible, whereas the last one should be more or less common sense in the meanwhile for anyone who wants to save at the energy bill anyway.

For preheating the fresh air in a passive way, the soil below the building (or next to it) is used. The fresh air passes the underground in slopes first where it is going to be warmed up in winter but cooled down in summer before it enters the air to air heat exchanger. This means you do not only safe heating energy, you don not need to cool in summer either as the concept goes into both ways.

So, you might say now that this is a very nice concept but who except for some never growing up hippies should build houses like that? Well, more than you would believe. The first Passivhaus appeared in the 90's already so its not even that "cutting edge" anymore anyway. In recent years many large scale projects have been launched. In the meanwhile not only one family houses, row houses and even communal housing have been built according to this concept but even numerous office buildings and a factory.

Alone in Austria there are already 1000 houses of that kind and their number increases exponentially.

Just to show you a small range of new Passivhaus objects alone in Vienna.

The last very important aspect has been not mentioned yet: the price. No horror stories here as the price of building a Passivhaus is about 10% higher than building a regular house. Having that said you have to keep in mind that the maintenance costs are considerably lower. It is estimated that the higher costs have been paid of in if I remember correctly 7 years. But if its a few years more dont crucify me.

And for all of you who want to experience how it is to live in a Passivhaus, in Lower Austria the first "Passivhaus village" has just opened where people are able to live for a few days in their passive house of choice on trial.

What do you think about it?
Aren't you asking youself as well, why the hell aren't there already more of them?

PS:
More information on it can be found here: Passive Houses

Wheeldog · 10-28-2007, 10:32 PM

The concept and design seem to be excellent. There is much we can learn from the Austria experience. Hopefully, American architects and community planners will adopt the basic techniques and apply them to U.S. buildings.

One problem we face is the huge inventory of existing homes and buildings that are poorly designed and insulated resulting in huge energy losses. What is needed is an effective way to retrofit existing buildings and substantially improve their energy efficiency. In addition, there would have to be tax credits and other incentives to encourage increasing building energy efficiency.

Slartibartfas · 10-29-2007, 02:55 AM

Quote:

Originally Posted by Wheeldog

The concept and design seem to be excellent. There is much we can learn from the Austria experience. Hopefully, American architects and community planners will adopt the basic techniques and apply them to U.S. buildings.

One problem we face is the huge inventory of existing homes and buildings that are poorly designed and insulated resulting in huge energy losses. What is needed is an effective way to retrofit existing buildings and substantially improve their energy efficiency. In addition, there would have to be tax credits and other incentives to encourage increasing building energy efficiency.

There exist already successful cases were older buildings had been transformed into Passivhäuser, but thats indeed not always that easy. To adopt them to low energy standards is however normally not much of a problem. While being not as superior as the Passivhaus standard, it still saves have of the needed energy in comparision to the status quo.

In Vienna especially the communal buildings often from the post war age, with terrible an energy efficiency of have been in countless numbers updated to low energy standards.

As far as I know the Passivhaus trend is mostly located in the German speaking area of Europe: Germany, Austria and Switzerland, but its not limited to those countries, you also find them in other European countries and not to forget, the USA has three of them as well

I expect that there are competing standards as well in other countries, but I doubt any one of them with comparabll efficiency has already a comparable number of existing buildings.

Slartibartfas · 10-29-2007, 03:30 PM

Quote:

Originally Posted by neorealist

how expensive is this to build?

As I mentioned above you can take the rough estimate of 10% more than a regular European home (which are normally always massive built).

To give you hard numbers. I read somewhere an offer for a Passivhaus for the costs of 1500€ per square meter. This specific house has a energy consumption of 13 kWh/(m²a) (Austrian climate I guess). (Passivhaus limit is 15kWh/(m²a)). That price includes housing technology. I guess that you have to pay additionally for furniture etc. Heating power is in this model produced by the small photovoltaic panel on the balcony. (Photovoltaic is however not a part of the Passivhaus concept but simply an upgrade to the extremely low heating demands)

This offer looks however like a pretty high quality one, and its an all in one offer. If you get involved yourself in the construction of your house you can get a Passivhaus considerably cheaper. Principally you can build it all alone as well, you should just educate yourself appropriately are engage a specialist for the planning part.

Calculated for Europe it is said that the break even is reached within at least 10 years I think. That means that after ten years a conventional house comes more expensive than a Passivhaus.

So you have higher initial investments but actually the Passivhaus is considerably cheaper calculated over its life span. And the higher energy prices are rising the more this will increase.

Quote:

Also, it seems to focus on heat retention, what about warmer climates?

Thats the fine thing about them, they work both ways. In winter they hold it warm, and in summer cool. Of course you might adopt it if its main purpose is to hold it cool (especially reducing the impact of solar power). If you have hot summers and cool winters a very nice solution is to have an intelligently designed roof that lets the winter sun in while the summer sun does not reach the windows. (exploiting the different angle of sunlight in the different seasons).

The preheating for the winter works in summer as precooling as the soil a few meters below the house has always a rather constant temperature that lies in winter above outside temperatures and in summer below them. I think if I remember correctly cooling the outside air 10°C (50°F) down is within the range of possibility.

Also the air to air heat exchanger goes both ways, in summer it cools the fresh air down and warms the exhaust air up.

A bloody estimation from my side would be that in case your temperatures are not longer than for a perhaps 2 weeks at once far above 35°C (95°F), you would not need any a/c for the home in order to maintain comfortable temperatures inside.

In case you live in a climate where you have hot days but cool nights, you can have very high temperatures and still have a cozy home, as you simply have to open the windows at night. The house is so good insulated that it won't heat up much at all during the day.

In short: The Passivhaus concept works for both ways, for cold and for hot seasons. You only reach its limits when the weather tends to very extremes. But even then clever design can adopt it, and if it really reaches its limits you still have to keep in mind that you just have to cool (or heat) the few additional degrees above (or below) the limit. You still will be able to save the greatest share of the heating or cooling bill.

Slartibartfas · 10-29-2007, 05:04 PM

I just wanted to add something regarding the price. If the city of Vienna can afford to build social housings (you know with the apartments for the lower middle class or working class) in Passivhaus standard, it should be somewhat affordable.

I think it might be interesting. Its today in the newspapers that the city of Vienna decided to build in a city development area to raise a Passivhaus settlement with 740 apartments in total. That will be the largest one in Europe so far, and therefore most likely also in the world. I would really be surprised if other cities won't follow over the long... Construction will long from 2008 to 2010.