Would you like to make your current house more energy efficient?

Is there something that is holding you back from upgrading it?

In this article, architect Marion Baeli from Paul Davis + Partners shares some of the key findings from the Retrofit for the Future programme. She is also author of new book Residential Retrofit: 20 Case Studies.

If you're anything like me you think the idea of retrofitting your house is a good one. You can lower the running costs, increase the comfort levels and do your bit for the environment at the same time.

Where it gets a bit hazy is in what this will mean in practice. Will your house end up looking completely different? Will the investment be worth it? Will you hire contractors that really know what they're doing? It's not helped by the fact that every house is different!

Retrofit for the Future

In 2009 there was a UK government funded programme called Retrofit for the Future, whereby £17 million was allocated to retrofit 100 properties in England and Wales. The houses included everything from period properties with solid masonry walls to more modern steel and timber frame constructions – in other words a complete cross section of the UK housing stock. The strategies were different too – insulation on the outside, inside or a hybrid of the two.

The whole exercise was about learning but each project was aiming to fulfil these main criteria:

• 80% reduction in CO₂ emissions (compared to 1990 emissions)
• CO₂ emissions limited to 17 kg per m² per year
• Primary Energy limited to 115 kWh per m² per year

A few years down the line and all the projects have been completed, and the data from them has been analysed. While, overall, the houses did not meet the targets there was a significant improvement in all of them.

• 70% reduction in CO₂ emissions (compared to pre-retrofit), which is just 10% short of the target.
• CO₂ emissions were 26 kg per m² per year, which is 15% above limiting target.
• Primary energy demand was 161 kWh per m² per year. Although 40% above the limiting target, this still represents a 67% reduction from the primary energy demand pre retrofit.

 

1. Any House Can be Retrofitted

One key takeaway from this programme is that all the houses were retrofitted! There was never a concern that one of the buildings would have to drop out because it just couldn't be done.

Marion Baeli says: “Obviously some are easier to retrofit. For example, a terraced house has a form factor that is more forgiving than a detached bungalow house, which has a lot more surface area so therefore a lot more heat loss area. So there’s a lot more work, a lot more insulation to put in as opposed to a terraced house. Some houses are easier to achieve a significant reduction in energy demand than some others.”

2. Retrofits Are Disruptive

If you're thinking that a retrofit is an easy way to transition to a low energy building then think again. For example, even if you are only doing work externally the need to change windows will affect the internal decoration of a room.

All teams commented on the level of disruption, so go into a retrofit realising how disruptive it will be.

Although Retrofit for the Future was not about phased retrofits, it's worth bearing in mind that if you did tackle your house in phases that each phase would be disruptive. You need to weigh up whether it's better to wait until a point where you can do it all in one go.

3. Do it Properly or Don't Do it at All

While you're going to want your retrofit to be as cost effective as possible, don't compromise on quality as it will backfire.

Expect a retrofit to be expensive as Marion explains: “It’s better not to do anything rather than trying to do something for £10,000, I think, because you’re going to end up with a project that is not holistic or a series of measures that are not comprehensive and are not working with each other. So if you do the insulation but not the airtightness or not the windows you’re going to have condensation issues so it’s important to understand a retrofit as a whole house measure.”

Your retrofit will need to address the insulation, airtightness, ventilation, thermal bridges and so on. Even if you only did one area of your house you can't pick and choose the elements, it must be cohesive.

 

4. An Experienced Project Coordinator is Critical to Success

Communication is very important on site as work is carried out. There are still many tradespeople who are retrofit virgins, so it makes the role of a project coordinator all the more important. That person needs to have a broad knowledge about everything to do with the retrofit and also be able to make sure that each different company understands the work of the others and respects it. This team collaboration must exist. If the electrician, for example, doesn’t understand the concept of airtightness and drills on the membrane everywhere, it’s going to compromise the overall performance of the house.

 

5. Not All Retrofits Reflect in the Value of the House

While you would think that retrofitting a house would add to its value, that is not necessarily the case. Therefore retrofitting may make more sense in places where the property prices are higher, such as London.

Marion illustrates with a case study: “One of the houses that I’m looking at has been retrofitted and the cost is about £110,000 or something like this for the whole retrofit, including energy saving measures and non energy saving measures so bathroom, kitchen etc. but the house is only worth £90,000. Do we demolish these houses and just build brand new?”

Demolishing housing stock comes with its own issues. The Pathfinder Housing Market Renewal scheme in the north of England was traumatic for the communities involved. They had to come to terms with being relocated while their old houses were knocked down. There is also the embodied energy to consider.

“There’s a lot of papers that have been written about the environmental cost of demolishing – rebuilding versus retrofitting. Of what I’ve read it seems that retrofitting is more environmentally worth it because there’s so much embodied energy in the house already that it’s better not to waste it. And the embodied energy in the new materials that you introduce in a retrofit can be paid back in terms of CO₂ cost fairly quickly – in 10 or 15 years maximum, even a bit less depending on what you’re doing.”

 

6. There are Economies of Scale When Retrofitting

Retrofitting your house is great, but if there were some way of doing a whole street retrofit this would be far more efficient. The main hurdles to jump would be how to get a group of private owners to work together and also how a collaboration like this would be financed.

Interestingly the greatest strides in retrofitting are being made by housing associations as Marion explains: “One of the reasons the housing associations are retrofitting is because they’re sick of having tenants complaining about the lack of internal comfort. The amount of money they’re spending trying to make their tenants happy and trying to find solutions against condensation is so important in their budget and in their time. They’re really interested in looking at whole house retrofit – big measures to resolve it once and for all. I’ve discussed this with several housing associations and they’re all saying this. It’s just so time consuming to deal with complaints of poor internal comfort.”

 

7. There's a Lack of Understanding Around Low Energy Building

Perhaps most surprising is the lack of understanding that the general public have around retrofitting. You're not going to want to upgrade your home if you have a fear of living in an airtight house! There was also confusion that a low energy house actually might be one where you wouldn't be able to have a TV or other gadgets.

Marion recounts how perceptions change: “The tenant of the retrofit that I did, everybody told her that she was mad to go into this project and live into this eco house. Now they all want to live with her because in the winter she wears t-shirts because it’s 23 degrees and it’s 16 in their houses so they’re kind of seeing the benefits of it.”

Ongoing Research is Necessary

The houses that took part in Retrofit for the Future averaged a 67% reduction in primary energy demand compared to before the retrofits, which is a considerable difference. While it may show that achieving an 80% reduction is not possible, close to 70% is possible on all sorts of types of properties. It is also still a new domain. More research is needed into costs, procurement, training and methodology.

 

Marion Baeli's book Residential Retrofit: 20 Case Studies aims to inspire people into action by showing them what others have already done. Marion also believes that we should embrace this as an opportunity rather than considering it a daunting challenge. There are 100 properties that have been retrofitted to this standard (in the UK), so the skills are in the market and these people can do it again.