District Heating – does it work with Passivhaus?

Cost effective district heating schemes need a nice dense energy demand. They also involve a lot of circulating hot water, which with the best will in the world, is going to involve continuous heat loss. Highly-insulated low energy buildings need very little heat – and in the summer, heat gains can be a positive menace.

So can the two work together? I explored the question a bit in this article for Passive House Plus – downloadable here as a pdf.

District Heating – does it work in Passivhaus?

Passive House goes large

Passivhaus is no longer just the preserve of the self-builder: more and more large Passivhaus schemes are being announced. These include both non-domestic buildings, for example in schools and universities,  and multi-housing schemes, generally in the social rented sector, though sometimes with a portion for private sale.

In this article for Passive House Plus magazine I looked at some of the economies of scale available on larger Passivhaus projects, and some of the obstacles that larger schemes may run into. Also, following from my previous article on the cost of Passivhaus, I looked a bit further into the economics of Passivhaus from the point of view of developers and owners – in both the domestic and the non-domestic sectors.

Read the article in pdf here: Passive House goes large

My thanks to Passive House Plus for the use of this document.

The cost of building passive

Passivhaus (Passive House) is often thought of as being “too expensive” for the mainstream. There are some designers and developers however who are managing to shave the capital cost premium down to just a few per cent – or even zero.

In researching this article for Passive House Plus I learned that the extra costs, where they are incurred, seem to derive from two main sources:

  • Passivhaus components tend to be more expensive than the “conventional” alternatives – though this difference is diminishing all the time; and
  • There is a “learning curve” in first (and probably second and third) Passivhauses for any team, where designers and contractors alike need to spend a bit longer working out how to co-ordinate their activities to ensure that details are buildable, and that built quality matches up to the standards sought.

The extra costs are mainly up-front; looked at over the building’s first decades of lifetime, running cost savings – including maintenance, and even cost associated with tenant dissatisfaction – start to pay back the initial investment.

Of course a key question is “costs compared to what?” – and as statutory building standards edge upwards, you might expect the “standard” and Passivhaus build costs to converge – thus, for example, mechanical ventilation is increasingly commonly installed in non-Passivhaus dwellings, simply because Part L of the building regulations is looking for more energy efficiency and hence higher airtightness.

However, a couple of caveats:

  • Mainstream dwellings built even to high notional standards may employ cheaper construction “models” with less quality control, and therefore, leave bigger performance gaps; and
  • Passivhaus is offering more than just energy savings, it is also concerned with comfort and occupant health – something that has clear value, but is perhaps hard to price in the context of a shortish article.

I was particularly interested in the perspective from some of the people I spoke to, suggesting that insulation (literally!) of occupants from rising and unpredictable energy costs was not only attractive to owner-occupiers, it was also attractive to landlords and to lenders, as problems with soaring energy bills appear to be playing an increasing part in rent and mortgage arrears – making a Passivhaus building a better bet for investment.

Several people suggested to me that if building standards (and testing standards) were set higher, “levelling the playing field”, this would reduce the competitive advantage of low-efficiency, shoddy building – and with it, reduce the cold wind that whistles though the performance gap and straight into occupants’ wallets.

Unfortunately, to bring about this kind of improvement, I can’t help feeling big developers would have to devote less energy to lobbying for the status quo, and more to changing their modus operandi. But with the first record of a Passivhaus building (in Frankfurt) offering heat “too cheap to meter”, customers may yet demand the same here.

Read the article in pdf here: The cost of building passive

My thanks to Passive House Plus for the use of this document.