Establishing energy saving priorities

So far in the discussion we have looked at several things that could be done and the ranges of levels of possible improvement that could be achieved. Now it is time to start to focus in where the real effort (and budget) should be placed. It’s time to establish a priority order and a good place to start is with the AECB list.

First we should understand the three categories of energy performance that the AECB recognises, Silver, PassivHaus and Gold. Note that these levels are all aimed at new construction but can be adapted for refurbishment projects like ours.

The Silver level is aimed at designers and builders who are relatively new to the demands of energy efficient construction. It does not make many demands for new or exotic material use, but does demand careful product and material selection and good attention to detail at both design and construction phases. Estimated saving for a typical dwelling is 60% to 70% reduction in CO2 emissions.

The PassivHaus standard has already been discussed, please see the blog post “When is a PassivHaus not a passive house?” PassivHaus methods maximise the use of energy efficient technologies. Estimated saving for a typical dwelling is 80% reduction in CO2 emissions. Some items required, e.g. high efficiency windows, are not readily available and so expensive.

The Gold standard is primarily to PassivHause performance standards for the building but with some detailed improvements and the addition of energy generation making the total energy used by the dwelling equal is better that a 90% saving over a period.

AECB Priority List
Item Description Applies to
1 Good levels of insulation Silver upwards
2 Minimal thermal bridges Silver upwards
3 Advanced windows PassivHaus up
4 Airtightness – Good level Silver
4 Airtightness – Excelent level PassivHaus up
5 Effective orientation for winter solar gain and summer cooling Silver up
6 Ventilation

- Mechanical exhaust only or MVHR

Silver
6 Ventilation

- Efficient MVHR

PassivHaus
6 Ventilation

- Very Efficient MVHR

Gold
7 Space and water heating

- Low power gas condensing boiler

Silver
7 Space and water heating

- Highly efficient gas boiler with solar supplement

PassivHaus
7 Space and water heating

- Large solar heating supplemented by Low power gas condensing boiler

Gold
8 Lighting

- Compact fluorescents or similar

Silver
8 Lighting

- High efficiency fluorescent lamps

PassivHaus up
9 Electrical Appliances A+ or better Silver or Gold
9 Electrical Appliances normally A++ PassivHaus
10 Onsite electricity generation to offset normal consumption Gold
11 User’s Guidebook All

The next set of blog posts will examine each of these in turn and assess their applicability and priority to our situation.

Leave a Reply