Natural ventilation often fails – but what is the evidence that mechanical ventilation succeeds? – Investigation for Passive House Plus
There have been a number of studies showing that natural ventilation, dependent as it is on random gaps in the building fabric and the vagaries of wind and weather, is not a reliable source of fresh indoor air. (see here for my article on this)
In theory, mechanical ventilation is under more control, and should work more reliably. But does the evidence bear this out? Does mechanical ventilation deliver good air quality in practice?
I looked into the research to find out whether MVHR, in particular, lived up to the ideal. Continue reading
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?
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.
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. Continue reading