How building regulations have tightened up over the last 50 years
We often talk about U-values here at TheGreenAge – these have changed considerably over the years as building regulations were bought in to help improve the energy efficiency of properties.
We have previously written about building regulations not going far enough, but over the last 40 years they have actually improved considerably as you will see below!
The first building regulations that had an impact on energy waste in the home came in to play in 1965 and these introduced limits on the amount of energy that could be lost through certain elements of the fabric of new houses.
Although building regulations are regularly updated, the iterations that really impacted the energy efficiency of homes were 1976, 1985, 1990, 1995, 2002, 2006 and the latest in 2013. In the article below we are going to show how building regs have changed for both walls and the roof (i.e. loft space). Together, these make up the majority of the envelope of the property (the envelope is made up of the roof, the walls + windows and the floor) and accounts for the majority of heat loss from the property.
HISTORIC U-VALUES OF WALLS
The efficiency of walls was an obvious area to be targeted since for many properties, the wall area represents the largest volume of the thermal envelope (the outside of the property where heat loss occurs from) therefore if you make that more efficient, it will have the largest impact on reducing energy bills and lowering energy demand.
The only real complication with the U-values of walls was that in 1976 building regulations defined walls as either exposed or semi-exposed. A semi-exposed wall is one that is exposed to the outside air via an unheated space, for example imagine a garage in the home, the wall between the garage and the main house would be a semi-exposed wall.
Anyway, below you can see how the u-value changed over time – remember that a smaller u-value shows a more energy efficient element, i.e. the movement of heat across the element takes longer.
1965 the required u-value for walls was 1.7
In 1976 as a result of the 1973 oil crisis, building regulations reduced the required u-value down to 1 (but it remained 1.7 for semi-exposed walls).
In 1985 the required u-value dropped to 0.6 for walls, hence many properties began to be insulated (this is about the time we begin to see cavity wall insulation installed as standard). The required u-value for semi-exposed walls dropped too – down to 1.0.
In 1990 the u-value for walls dropped down to 0.45; this meant that cavity walls were built with thicker cavities so more insulation could be installed. The required u-value for semi-exposed walls dropped down to 0.6.
In 2002, the u-value for walls was reduced to 0.35 and now building regulations stipulate the u-value for a wall should be just 0.3, quite an improvement from 1.7 in 1965!
Historic U-Values of the roof space
An uninsulated loft space would have a u-value in the region of 2.5 W/m2K, but in 1965 building regulations dictated that the maximum u-value for a loft should be 1.4 W/m2K – which could be achieved with just 2.8 cm of wool insulation!
In 1973, the required u-value dropped to 0.6 – this required a 7cm thick layer of wool insulation – again not much compared to what is needed now!
In 1985, the u-value dropped to 0.35, in 1990 it dropped to 0.25 and in 2002 this dropped down to 0.2. To achieve a u-value of 0.2, you would require 20cm of mineral wool insulation.
Nowadays the u-value required for roofs (and loft insulation) is 0.17 W/m2K – this is 250mm of wool insulation – so in effect you now need 10 times as much insulation as 50 years ago to ensure you conform – that is quite a lot more!
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