Passive House too difficult to achieve?

There are some instances where a client may decide that achieving a Passive House standard for new build or EnerPhit Passive House standard for retrofit is going to be too difficult but would still like to build or retrofit a low energy home that is a great improvement on the current building regulations.

Reasons for this may be because planning permission has already been granted for a building that was not originally designed as a Passive House and is unable due to constraints such as building shape (form factor) to be able to hit Passive House targets. Or in the case of an existing building the form factor, orientation, location, construction type and  planning constraints may make EnerPhit impossible. Alternatively a chosen contractor or developer may not feel they have the experience or expertise to build a Passive House.

Building an “eco” house to no particular specification or guidelines can bring with it a host of problems such as under performance, overheating or air quality issues that would undoubtedly leave a client unhappy with the results. It is far better to design and build to a specific criteria and this is where alternative Building standards can be used as a measure of performance.

What are the alternatives?

The AECB Building and Retrofit Standards

The AECB building and Retrofit standards use PassivHaus principals of a fabric first approach and promotes the use of PHPP (Passive House Planning Package) software to model the energy requirements but with less onerous targets than PassivHaus.

By focusing upon a fabric first methodology, you can make the most of passive and low energy design and technology. This serves to reduce energy demand and minimise lifecycle cost.

The AECB Building Standard is aimed at those wishing to create high-performance buildings using widely available technology. We estimate that this low-risk option will reduce overall CO2 emissions by 70% compared to the UK average for buildings of each type – a highly significant result given the relative ease and low cost with which this standard can be met. Individual self-builders and large-scale residential and non-residential developers could make a valuable contribution to low-carbon building by meeting the AECB Building Standard.

How are AECB Standards certified?

New builds and retrofits can be self certified by a Passive House Consultant so this is something I can do without input from a third party certifier. This reduces cost but still shows that the build has met its target requirements and has been built to a suitable standard.

AECB Building Standard
AECB Retrofit Standard

LETI Retrofit Standard

Like the AECB retrofit standard, the LETI retrofit standard uses Passive house principals and modelling and has its own target levels suited to UK housing stock.

On smaller projects or where finances may not be available it is possible to follow the LETI retrofit fabric and systems targets that do not require the expense of a PHPP model.
The flow chart below gives a really useful guide to help clients make a choice about what their targets for their home may be. Click images to enlarge.