Why the Scottish Green Party won’t solve the climate change challenge ( Part 2 )

The second myth and lazy assumption peddled by the Scottish Green Party is that it would be relatively easy and inexpensive to insulate our homes and buildings to a high standard, such that they can be easily heated by a heat pump. All that is missing, they repeatedly claim, is the political will to do so.

It is relatively easy, albeit expensive, to insulate to a high standard in a new build home. Indeed Scottish Building Standards ensure that you have no alternative. To do so in a retrofit situation is quite a different proposition.

The most effective class of commonly used insulation is made from polyisocyanurate. This is the type of insulation that was used in  Grenfell Tower and which contributed to the horrific fire. The public enquiry discovered that the manufacturers had falsified the flammability tests and that this was a significant factor in this appalling disaster. Of course any builder could have told you that this insulation burns well. When it does so it gives off cyanide gas. It is a noxious material and although there has been no detriment to health yet proved in normal use, I would not be surprised if a health risk eventually emerges.

A further problem with this insulation is cost. For 200mm thick insulation, sufficient to give a standard of insulation similar to a new home, the cost is around £50 per sq metre. Passivhaus standards require an even greater thickness of insulation. To completely wrap an average home in an envelope of insulation of this thickness will set you back around £20k just for the insulation. To minimise gaps and to deal with shrinkage of the boards the insulation is best applied in layers and this contributes to the cost of installation which is not insignificant.  

Of course other types of insulation are available but they are not so effective and therefore to give the same standard of insulation have to be thicker. The thickness of insulation generally required to reduce heat loss to the required standard is a significant problem as I will explain later. From time to time some new ‘ thin’  insulation material appears, claiming superb insulation qualities complete with bogus tests and data. One by one over the years these have been discredited. As Mr Scott used to say, ‘Ye canny change the laws of physics’.

Thickness is a problem because to reach new-build standards you have to wrap the whole building in at least 200mm of high performing insulation ( e.g. polyisocyanurate or similar ). This can be done externally or internally. Installing the insulation on the exterior of the building is both the cheapest and the most effective way to do it. Unfortunately only a proportion, perhaps around 25%, of our buildings lend themselves to this approach. Even then the ancillary costs on top of the cost of insulation are very significant and likely to be much more than the cost of the insulation itself. ( Witness the huge remedial costs being faced by home owners whose properties were given the Grenfell Tower cladding/insulation treatment)

Of the case studies chosen and highlighted, by an industry that stands to make billions from our rush to insulate, the focus is on the low hanging fruit of easy to insulate buildings. Even then they rarely insulate to the standards of a new home and the result is therefore at best a partial solution to the problem. Applying 50mm of cavity insulation or 50mm of insulation and cladding, although better than nothing , doesn’t really cut the mustard when it comes to properly insulating a property. As the Scottish House Condition Survey suggests most of the low hanging fruit with regard to insulating our homes has already been picked. This has been worth doing but has got us nowhere near the standards of insulation naively and routinely demanded by the Green Party.

The real difficulties emerge in the very significant proportion of our housing stock (perhaps as much as 50% ) where insulating on the outside is just not possible. Traditional tenements are just one example of this ‘hard to treat’ type of housing. Imagine adding 200mm thickness to the walls of your home on the inside. This could mean losing around 10 percent of your floor area. In many cases the effect would be to reduce a three bedroomed home to a two bedroomed home. Partitions may have to be moved. Many floorplans just wouldn’t work at all. Rewiring may well be entailed as sockets and switches wouldn’t necessarily stretch to the new face of the wall surfaces. A certain amount of re-plumbing would be required. Radiators for example would have to be rehung. Toilets and bathrooms if they remained viable may have to be altered. The property would have to be re-plastered, kitchens may have to be removed and re-fitted.  All of this is before you  consider insulating the floors. Where such comprehensive insulation treatment could be successfully done I would expect the cost to be at least £100k ( and perhaps much more ) for a two bedroomed dwelling.

Adding to the problem is the question of air-tightness. Passivhaus standards and increasingly Scottish Building Standards call for air-tightness. This causes real concerns from those who understand the problems we could face with such an approach in Scotland’s very damp climate. Often such suggestions emanate from politicians who go on a jolly ( sorry, I should have said ‘fact finding mission’ ) to Northern European countries that have very different climates and approaches to housing than we have. In such countries annual rainfall is typically 500mm per annum. In the West of Scotland annual rainfall can reach as much as 4,500mm per annum.

The traditional solution in our damp climate has been to make sure our buildings are ventilated and to allow them to ‘breathe’. Sealing up ventilation and making our buildings airtight in an effort to improve energy efficiency carries a high risk of problems caused by dampness appearing over time ( Not to mention health problems in occupants ). The trouble is that when such problems eventually manifest themselves a considerable amount of damage may already have been done. If such problems do occur solutions will come with a very hefty price tag.

To make matters worse government grants have had the result of increasing insulation prices and as you might guess the fast buck merchants have piled into the insulation sector. As usual the grant schemes and government insulation programmes are heavy on bureaucracy and light on the competency of contractor or quality of work.

A further complication is the methodology used to determine the energy efficiency of our buildings. It is a UK government methodology known as The Standard Assessment Procedure and commonly referred to as SAP. It is a kind of half clever and half-crazy algorithm which is just complicated enough to frighten off proper scrutiny. This unfortunate formula forces some perverse ideas on building design as well as some that are just plain daft.  

Admittedly that is a conversation for the handful of nerds in Scotland who properly understand the SAP calculation but it is one that is worth having, all the more so as Building Standards are wholly devolved to the Scottish Parliament. Mysteriously after over twenty years of devolution,  we remain wedded to this unfortunate UK methodology.

In conclusion it is not at all as easy to significantly improve the energy efficiency of our buildings as the Green Party suggest. That is not to say that we cannot take further clever and careful steps in this direction or that there are not many worthwhile things that Scotland could do to significantly reduce our carbon footprint. Indeed I would go as far as to say that Scotland could be a world leader in tackling climate change but not if we listen to the theoretical hocus pocus of the Green Party.