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Fabric Energy Efficiency

Some of the critique leveled at building regs in the UK is the lack of heed paid to fabric energy efficient that is why from 2013, part L of the building regulations will introduce a minimum standard for Fabric Energy Efficiency. Fabric Energy efficiency is a key concept in energy efficiency, after all before installing solar panels etc. we should consider energy efficiency. This is the norm on the continent with standards such as Passive House (Passivhaus). Employing extreme levels of fabric energy efficiency. To the point where they do not even need heating!

Elements of achieving high fabric energy efficiency;


Insulation has been added to houses for decades, in loft spaces from the 70s onwards and started to appear in walls and floors in the 90s.

Door and Windows (Openings)

Door and windows often prove to be chink in the insulative armor of a building. A typical wall might have a U value of around 0.3, whilst a fairly high performance window will still only achieve around 1.5 U value. Code for sustainable homes requires excellent fabric energy efficiency and also good daylight lighting. So they is a balance to be had here . . . huge windows lead to poor overall insulative qualities, and possible reduction of fabric energy efficiency. There are windows that offer very high performance such as those designed to the passive house standard. Passive house windows can have U-value of 0.58 W/m²K.

Air Tightness

Even a well insulated house will not stay very warm if it is drafty. This is why for high fabric energy efficiency we must work to achieve very low air permeability in a house.

This normally involves lots of tape:
air_tightness air_tightness

Other Thermal Properties

Thermal mass should also be considered.