1. Are the requirements of the Passivhaus standard clear?
The general impression is that they require further translation. Not every aspect of the design criteria entirely agree with UK requirements and understandings (primary power vs CO2, DHW provision....German consuptin figures not UK one etc.)

2. Are the values set at the right levels? If not, too high, to low?
Arguably the PassivHaus standards could withstand some reappraisal, it is 15 years old after all. The AECB have refined/updated the PassivHaus standard for use in the UK (the AECB Gold standard) complete with CO2 performance targets. (Check out the AECB website for a downloadable copy of the standards.)

3. Would the PassivHaus standard work as it is in the UK?
In principle, yes, though the occupant may have to make certain lifestyle changes. Certain refinements to the standard may be required in order to ensure greater acceptability in the UK, seeitem 1 above. (The greatest challenge is ensuring that the technical and construction challenge is ensuring that the airtightness standards are met.)

4. Would you be happy to live in a house with continuous mechanical ventilation?
Sweden and Canada have being using MVHR for 25+ years. The step change is a psychological one only.

5. Do you feel that designing homes to the standard would achieve high levels of the CSH without additional cost?
No. In terms of capital cost PassivHaus standard projects tend to cost 10-15% more, though this additional cost is more than recouped within the life time of the property (Try to think in terms of cost/kWh-saved rather than strict payback periods. This allows for easier comparison to mains gas or electricity which is purchased in cost/kWh)

6. Super insulation, air tightness and attention to solar gain / shading, or.. on site renewable energy generation?
PH standard looks at the first three and then bolts on on-site renewables. Why? This is the most cost effective approach (cost/kWh-saved for renewables is not as good as super insulation, air tightness and attention to solar gain (and other energy efficiency measures).

Vocation: Architect

Thanks both.

Mark, I'd heard of the AECB standards but had no idea they were an updated version of the passivhaus standard. Thanks very much for all your info.


Emily

Emily,

Why don't you check out your own University? Specifically, Prof Brian Ford at the School of the Built Environment is working on a paper on whether Passivhaus standard works as well in warm climates, due for publication in the next few months and for presentation at an event in September.

I got the wrong Nottingham Uni, but never mind, it sounds like you are talking to all the right people. I think the natural ventilation v MVHR debate is set to run for a while yet.

Best wishes

Keith,
The reason for me stating earlier that AECB Gold is a refinement/update of the PassivHaus standard is due to the fact that 1) The AECB Gold standard sets a specific CO2 threshold rather than a Primary Energy requirement, and in doing so also establishes a more rigorous and demanding refinement of the PassivHaus standard; this is a globally relevant update, and 2) where the PassivHaus standard permits electric resistance heating, the AECB standard does not (this is perhaps more UK specific, though not necessarily).

Does AECB Gold establish lower energy consumption target kWh for kWh, not to my knowledge. But the Emily’s earlier question was about "values" not energy. The question "Are the values set at the right levels? If not, too high, to low?" is open ended, it is not specific to energy (which is one interpretation). The AECB’s initiative to introduce a new value, that of CO2, into this context is relevant. By only seeking to consider Primary Energy the PH standard can be responsible for greater CO2 emissions than need be the case, so when one asks “are the values set at the right levels?” though the answer is not entirely straight forward the answer is no.

Update or refinement? Any refinement is by virtue an update. We can all be fairly certain that CO2 targets are likely to play an increasing role in the future, not only within the UK but globally. In the USA the Architecture2030 campaign has been considering developing CO2 targets (the stumbling block is that such CO2 emissions data for electricity in the US is not currently available in all the States as a consequence they have been unable to implement this strategy.)

So are the PassivHaus standard and AECB Gold to considered the same standard? My answer to that is no, not to my mind at least. AECB Gold is an refinement and update of a 15 year old standard. (Whether is this is the official line of the AECB I can not say.)

Mark