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Graham Dow and Marbank Construction’s U Values Beat PassivHaus and the Building Regs

Another EPC A rating achieved

Since then, we’ve done a PassivHaus Planning Package assessment based on the drawings, a Design Stage SAP and an EPC. And because the development must meet CSH Level 3 to comply with a planning condition, we’re also working on Code for Sustainable Homes (CSH). The achieved EPC rating is an A – with a 63.2% improvement over the target emission rate (TER) – using a standard gas boiler.

U values beat building regs and PassivHaus standards

Graham and the Marbank team took a fabric first approach to give U values of 0.11 for the ground floor and external walls. The latter is particularly impressive as it beats the demands of building regulations (U = 0.3) and PassivHaus (U = 0.15). So, how were these figures achieved? For the external walls a thickness of 667mm holds the key: 100mm of facing brick, 100mm of insulation and 425mm of cellular clay block and plasterboard.

Details matter

The showcase specification continues with the component details, such as Schock balcony connectors to help stop heat loss on the balcony. Then there’s triple glazing and resultant U values of 0.8 – and a target air permeability value of 0.69.

Furthermore, the development draws on experience gained in the German market. It uses a German mechanical ventilation heat recovery (MVHR) system that’s PassivHaus-approved. And renewables play their part too, with five square metres of solar thermal and 3.25 kWp of PV (kilowatt peak).

A worthy category winner

Enthusing about the project, Sarah Fenwick, Energist’s founder and managing director says: ‘From using PassivHaus principles to little touches like blinds that automatically close when outside temperature changes, this project shows how to achieve exemplary running economies. It’s another worthy category winner.’

Jon Ponting

Author: Jon Ponting

This article was published by Jon Ponting on 23.10.2013.