Reading suggestions - please help!

Hi all,

I’m keen to improve my retrofit/local energy market knowledge, does anyone have any good books they can recommend?

It can be related to historical aspects or current challenges, or technical papers, I’d appreciate any suggestions!

Thanks very much



This is a great idea, and I am interested to see what people suggest! I will share this with our team and see if they have anything which they can recommend.

Hopefully if we get a good list together I can turn this into the basis for a Wiki post of recommendations.

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Hi James,
If you haven’t already seen the LETI Climate Emergency Retrofit Guide then I’d definitely say that’s worth a look. Free to download here:


Thanks very much Adam, this is really interesting!

In addition to the LETI guide I suggest James Traynor‘s ‘EnerPHit – A step by step guide to low-energy retrofit’.

Thanks for this Tim, I have placed it on back-order with Riba Books in an attempt to avoid giving Amazon any more of my money!!

@matt @mattfranklin this is interesting reading if you’ve not already stumbled across it!

Try Back to Earth for insulation advice - see below item

Energy Savings and Thin-Layer Insulation (internal)

We often get asked what is the best thickness of insulation to use when considering solid wall insulation and also whether internal or external insulation is best. As ever, this is not a straightforward question to answer because of all of the competing factors that have to be considered.

Starting with whether internal or external insulation is best for solid masonry walls, we would suggest that internal insulation is the most effective. Put simply, masonry absorbs a lot of infrared energy, even at 21C, and for other than a few weeks in the hottest part of the year, it is generally uncomfortably cold to touch or be close to. Therefore, if you insulate yourself from it you instantly improve the sense of comfort within the room.

The drive for very low U-values (the heat loss of a wall for a given temperature difference between inside and outside) ignores how we perceive comfort and is only looking at the overall loss of heat from a building. Low U-values also mean lots of insulation and also a high material and installation cost, both of which are barriers to use.

So generally, if you have the space to utilise internal insulation, this will give you the biggest boost to comfort for the lowest cost.

The next question is how thick should you insulation be. Again, this is subjective but we feel it is worth considering your current situation and comparing it to the savings created by adding the insulation, something championed by Mark Lynn of Thermafleece.

Starting with a solid brick wall, you may have a U-value of around 2 W/m2K, which is very poor for those not familiar with U-values! Directly fixing a 40mm layer of wood fibre insulation to the wall would typically reduce the U-value down to around 0.63 W/m2K or with 60mm it would come down to 0.48 W/m2K. Neither of these seem particularly effective when Building Control would like you to achieve a U-value of 0.28 W/m2K, but this requires 120mm of wood fibre insulation.

Looking at those figures differently, the 40mm achieves a 69% reduction in heat loss, the 60mm a 76% reduction and the 120mm an 87% reduction. Looking at the weekly savings in energy, assuming that on average there is a 10 degree difference across the wall and the house has external walls of 100m2, the 40mm would save you around 226kWh, the 60mm would save 252 kWh and the 120mm would save around 287 kWh.

This is all a rather long winded way to say that, at current energy prices of around £0.10/kWh, the 40mm boards would save you around £23 per week and by increasing this to 120mm insulation boards, you only save around £6 extra per week. The 40mm boards will still give you a massive boost in comfort, eliminate mould and subsequently improve indoor air quality and increase the value of the house.

With all this in mind, we would not instantly say that going for the lowest U-values is the best solution. Going for a minimum of 40mm of insulation is the best thing you can do but extra thickness will give you further, if incremental, gains.

The above advice is only partially true. Hopefully most people on this forum would like to reach Zero Carbon, whether or not it is practical for their property. To do that you need to avoid thermal bridges and have a very low U value for the whole house. EWI cuts out most thermal bridging and thicker insulation improves the U value. It is not just about payback in 3-5 years but over the life of the building.

Ideally you want 300mm of Rockwool equivalent surrounding the whole house. Top, bottom and sides. Obviously this is unlikely to happen in real life but it is a target to aim for.

Edit: With no gaps at the joins. Think of a tea cosy snuggly fitted on a thermal mat.

Observe the thermal bridges in this room. With external wall insulation they could all be avoided.


Hi Tim, I agree with your input for the ideal but there is also the optimum, sensible and what can be afforded and practical given the starting point is not the same for all. The post was for information and illustrate points to be considered. Ultimately we all want comfort and for each this may vary. Hope it has stimulated thinking in others.

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I agree that very few people can achieve the ideal, as my post indicated. Problems can arise if a “that will do” approach is taken. Imperfect solutions can prevent better ones from being applied later. It is better to do some of the job really well and then do more when it can be afforded than to spread the resources too thinly. This is covered by both LETI and EnerPHit phased approaches.