Reflections on energy and housing


Jenny Love, UCL Energy Institute

I’m going to be leaving academia in a couple of months. Aside from my colleagues being able to finally get some peace and quiet and not having their chocolate supplies taxed on regular occasions, there are some other benefits to this. One is that it has made me reflect on what I have learned whilst doing a PhD in energy and housing. Here are four reflections that you may find interesting.

1. We still don’t really understand a lot of factors behind energy use in buildings.

Much of the blame for this can be attributed to a poor evidence base for physical performance of houses. For example, not enough studies have measured energy use and linked it to real measurements of heat loss from the building. Researchers like Virginia Gori, Sofie Pelsmakers and Sam Stamp are working on these actual measurements.

If we don’t understand how energy is used in the first place, this makes knowing the effects of things like retrofit quite difficult to predict. Researchers like Ian Hamilton are using the best data we currently have to assess the effect of energy efficiency measures.

2. Social scientists and physicists/engineers must go further than just collaboration

We have an unfortunate tradition in our field of a lack of respect between physical scientists and social scientists. What I mean by saying we must go further than collaboration is not just working together and bearing with each other – but setting an example of genuine appreciation of the other’s discipline – including stopping dissing each other’s disciplines behind our mutual backs. When I started my PhD I didn’t know much about social science, and therefore used to be quite rude about it. Now I have come to see that it’s the people who bring about the physics in buildings that I like to study. For example, I described here how when houses are retrofitted, the outcome is determined by the amount by which the occupants adjust the heating. Researchers have to understand what made the occupants adjust the heating, and then the effect that this has on energy use.

The best combination of social science and physics in one project I’ve seen is the work Lai Fong Chiu and Bob Lowe‘s Retrofit Insights team are doing, here. As it happens, the two lead authors of this study are married. Now, although this happened before they wrote the study, there’s nothing to say it couldn’t happen the other way round – you never know, multidisciplinary collaboration could lead to love. In my role as Dr. Love I’m happy to point you towards eligible physical or social scientists with whom you could start a multidisciplinary collaboration.

Another person to keep your eye on is Adam Cooper of UCL STEaPP, who is doing great work in starting to develop the theoretical framework within which social science and physics can fit together in order to study energy use.

3. ‘Behaviour Change’, like religion, is (mis)used as an excuse for all kinds of wrongs

What I mean by ‘Behaviour Change’ is trying to get occupants to reduce their energy use by changing their home heating behaviour. This is only beneficial if there is actual evidence that occupants are exhibiting wasteful behaviours in the first place. In my case study sample in social housing, many of them were heating far less than average and trying to get them to turn the heating down would not only be morally wrong but also bad for the house (leading to more mould, etc).

The second problem I have with ‘Behaviour Change’ is that it is sometimes used as a pretend solution in order to avoid the real issue – the fact that our housing stock is among the least thermally efficient in Europe. We need to get on with insulating it, instead of trying to make people colder by using less heating.

I’m certainly not against occupant engagement. Quite the opposite. What I would recommend it looks like is firstly listening to the occupants about how they do use the heating, and then, only if they are up for it, deliver tailored advice which will help them meet their heating needs using less energy. Also. we should be giving advice on wider aspects of maintaining a healthy home, like how to ventilate adequately.

4. Separate energy/climate change policy from warmth policy.

A crude description of the way retrofit policies worked during the time of my PhD is that energy companies ‘offset’ their CO2 emissions by funding retrofit of social housing. There is very little measurement of whether energy or CO2 has actually been saved, but if there were, it would be seen that some occupants do not save energy but have a warmer home instead – in fact, this is what the occupants need. However, this would be counted as essentially a failed policy, even though the occupants now have a better quality of life. Maybe that’s why no one measures the actual savings.

There are two agendas going on here  – allowing people to be warm in their homes, which is very important, and mitigating climate change by reducing energy use, which is also very important but is the opposite to making people warmer. The more you do of one, the less you do of the other: in my mind, the trade-off is like this:

trade off

I think our climate change and energy demand reduction policies should not target
social housing – there are plenty of other places to focus energy demand at. This sector
needs policies measured in terms how much more comfortable the previously-cold
occupants become.


So, there are some thoughts. I invite you to challenge or add to any of them in the
comment section below. As always, feel free to contact me on if you would like to have a more detailed discussion on anything raised above or have any questions about energy and climate change in general.


Becoming Dr. Love: Part 2 (what occupants do)

Jenny Love, UCL Energy Institute

In my previous post here, I described the process of PhD data collection and some of the odd things which can happen when carrying it out. After publishing that post I went quiet for a bit to concentrate on the small matter of turning the data into a 90,000 word thesis. Having done that, and then recovering by alternating between sleep and eating nutella out of the jar, I am ready to face the world again. So in this post and the next one I’ll be describing some of my findings.


In this post I’ll talk about what light was shed on the complexities of occupant behaviour in the context of retrofit: how occupants change their heating behaviour afterwards, and why internal temperatures increase.  In the next post I’ll report some implications of this concerning whether our current retrofit strategy for social housing goes far enough.

What was I trying to find out?

There is a general concern that retrofit, here referring to insulation of dwellings, doesn’t save as much energy as it should for all the effort of wrapping a house up in a blanket. That’s because it is suspected that instead of what  is ‘supposed’ to happen (i.e. the occupants keep the heating at the same level after the retrofit and save energy), occupants will take this chance to heat to higher temperatures or for longer, and not save much energy after all. This is especially expected to happen in ‘fuel poor’ households: those who before retrofit struggle to heat their home to the temperature they would want, for whom insulation might mean they can be warmer.

As I described in more detail in the last post, instead of looking at just outcomes of retrofit  (i.e. these people saved X kWh of energy, or it was X degrees warmer in their house afterwards), I looked also at what actually happened in the homes: what did occupants think the retrofit was all about; how had they changed their use of heating since; were they using their home differently and was this requiring more or less energy? So the sort of things I was measuring were: their use of radiators, air temperature and humidity, and use of space;  I also interviewed the occupants before and after.

Variety in occupant reactions

When you wrap up a building in a big pink jumper (see photo below), it will lose heat less quickly afterwards, and so its average temperature will increase without the occupants doing anything.


But how occupants then react to this natural temperature increase is different in different households. I found three types of occupant reaction, ranging from occupants practically eliminating their use of heating to occupants using more hours of heating:

1. Temperature increase from the building, counteracted by occupants

Two of the case study households turned down the heating so much that the temperature went down after retrofit. However, they reported feeling warmer. How could both of these phenomena have come about? Here’s what I could gather from my data…

Both of these households had an income cut around the time of the retrofit and were really struggling for money. Also, before the retrofit they were both expecting the retrofit to lead to a warmer house with less heating needed. This could explain why they turned the heating down so much. But why did they feel warmer? I looked in the air temperature data: had the particular rooms they used got warmer at the times they used them? Or had the daily minimum temperature they experienced increased, say, when they got up in the morning? Neither of these had occurred. I had to conclude that there must be other comfort variables at work, like radiant temperature.

2. Temperature increase from the building, no change in occupant behaviour

These occupants carried on using the heating in pretty much the same way as before: they didn’t turn anything down, and they didn’t turn anything up. As was mentioned above and will be further explained below, this still leads to an increase in internal temperature.

3. Temperature Increase from the building, then occupants used more heating

Two different and interesting processes were seen in households who used the heating more after retrofit.

In one flat,  the occupant didn’t really bother with the central heating before the retrofit since the building was so leaky that it didn’t seem to make a difference. He heated the living room with a gas fire and stayed in there. After the retrofit he started using the central heating since it now actually did something.

In another case, even though the insulation made the house warmer, different rooms warmed up by different amounts. This had the effect of making the occupants’ bedroom feel cold, as it hadn’t warmed up as much as some other rooms. So they started heating the whole house all evening, so that their bedroom would be warm enough by the time they wanted to use it.

Turning heating up, down, the same…does that mean that anything can happen?

Yes. I will argue in my next post that with this type of ‘shallow’ retrofit (10 cm of insulation), it’s very difficult to predict the outcomes since you leave a lot of room for different outcomes to be possible, especially when new occupants move in. However we only started to see a glimpse of the range of possible outcomes. With the same people living there after retrofit as before, occupants probably aren’t going to massively increase their energy use after retrofit so we probably aren’t going to see those kind of outcomes.

Also, just because occupants reacted in a variety of ways, doesn’t mean that how they reacted totally determined the outcome. As we’ve seen, the building theoretically has a lot to do with it. We can try to quantify its influence in a few ways…

In most houses there was a temperature increase. What was it mostly caused by?

The answer is not the occupants but the building itself. How can I know this? By looking at when it occurred…

Firstly, most of the temperature increase compared to the previous year occurred when the heating was off. That is, the times when the heating was off, post-retrofit, were warmer than the times the heating was off pre-retrofit. I had a fancy equation to calculate how much of the temperature increase occurred during unheated hours, and it turned out to be 77-87% across the houses.

Within this, quite a bit of the temperature increase happened at night. It’s possible to see the houses cooling down slower at night, when the heating was off, whilst the occupants are fast asleep and therefore not thinking, ‘I know, I’ll increase the temperature in my dwelling’.

In some houses, the hours in which the heating was on got warmer after retrofit (accounting for 5%-23% of the temperature increase). This wasn’t due to people turning up the thermostats. It was either that the thermostat was at a sensible setting and the building was too leaky to get that warm before retrofit, or the thermostat was at a non-sensible setting like 30C (for whatever reason) and the heating system tried its hardest but still couldn’t reach it.

What to make of all this

The first point is that if the temperature increases in someone’s home after retrofit, it’s not necessarily their fault or their intention. To get the temperature not to increase, occupants would have to shorten their daily heating period by quite a few hours. Even when they increase their hours of heating, most of the temperature increase is still attributable to the building cooling down more slowly. So we can stop occupant-blaming.

not guilty

Secondly, there was quite a large range in terms of how occupants reacted, and whether they turned heating up or down, which makes it difficult to predict outcomes. However, this was a small range compared to what could have happened. I haven’t explained this statement yet, as I explore this further in the next post, where I talk about the effect of new tenants moving in over time –  and how the current way we do retrofit means we can’t guarantee energy savings afterwards.

That’s all for now – but feel free to get in touch with me if you would like any more detail on the sort of mechanisms I uncovered or if you have any questions:

Becoming Dr Love: Part 1 (what I did in my PhD)


Jenny Love, UCL Energy Institute

I have been blogging about energy-related topics for over a year now, and so far haven’t said anything about my own research. In this post and the next one (forthcoming), I’ll describe, hopefully in a fun way, how I went about doing research on making social housing energy efficient, and what I found out. This one, part 1, describes what I did and some of the adventures I had along the way.

The point was to go and find out why, when social housing is made energy efficient by putting insulation and double glazing in, not as much heating energy is saved as was predicted – instead, the house becomes warmer. Now, this could be because occupants find heating cheaper and decide to use more; it could be that they use their heating exactly the same after the insulation and the house keeps heat in better and so the temperature goes up; there are various other options.

Now, much as I love doing it, sitting in an office drinking tea and staring at graphs was not going to solve this one – I decided on a ‘mixed empirical methodology’ which involves going and finding out what is going on in the houses both physically and from the occupants’ point of view. On the physics side, I decided to measure (both before and after the insulation) temperatures, radiator activity (to find out how they used heating) and use of space (to find out if they were able to use more rooms in their house when the rooms got warmer). On the occupant side, I decided to interview people in their homes about their life there, the cold, the insulation, and other topics.

After gaining permission to do my research on a particular council estate, the first thing to do was recruit households. Now, other researchers use sophisticated-sounding ways to do this, such as ‘stratified random sampling’ and ‘systematic sampling’. Although it hadn’t been my intention, the method I ended up using to recruit people was: pity. Imagine: it’s snowing outside; you hear a knock at your door, and a girl and her friend are standing outside, teeth chattering. The girl is wearing oversized steel-capped boots she has obviously borrowed from a man, and a ridiculous yellow jacket like a lollipop lady. You have never heard of UCL Energy Institute and have no interest in what she is doing but since her lips are blue you bring her in and give her a cup of tea.

It was pretty much like that.

Some things stick with you when you go into random people’s houses. I now present an extract of probably one of the weirdest conversations I’ve ever had:

Occupant: “When we have the double glazing we’ll have to move Emily”

Jenny: “Emily?”

[Occupant points at very large model triceratops on the floor of the living room]

Jenny: “…Aah.” [for some reason the next thing that came into Jenny’ head was:]”For some reason I thought it was male.”

Occupant: “Oh, no. Listen to this: EMILY!”

Emily: “Raaaaah!”

Jenny: “Oh, it knows its name…”

Occupant: “Oh, yes. But it gets even better: put your hand in her mouth.”

Jenny: “I don’t know if I want to do that”.

[Jenny does it anyway]

Jenny: “Ooh, she’s teething me!”


So anyway, one month later I thought I had enough data from the houses, so went back to take the sensors out and interview the occupants. I arrived at the first house to be told that the children had taken the sensors down, and why had I put them up, they looked so much like toys. I apologised. I went to the next house and was told that the cat had taken the sensors down.

cat in 184 mary slessor

This very cat, yes, the one shown sitting here on my bag of sensors, out-intellectualised a PhD student by pointing out a flaw in her research design. I should invite it back to be my PhD examiner.

Aside from animal sabotage, some serious and quite sad things emerged in the interviews. One lady lived in the mouldiest house I had ever seen, and appeared to be trapped in a vicious cycle. She had COPD, which is a lung condition in which any cold caught goes to the chest and the sufferer ends up being rushed to hospital unable to breath. Her doctor had told her there was a simple way to stop this: turn the heating up to at least 18°C. But she couldn’t afford to do this. She was unable to work because of the condition, but that meant she was stuck in her house for longer, and couldn’t afford to have the heating on, so got more ill, so couldn’t work…etc…. I was wondering if the insulation would help break this cycle. I had never realised how important housing condition is in people’s lives. Staring at graphs or being in a lab would never have brought this kind of insight to my attention – you have to get out and chat to people in their own context.

After taking down all of the sensors which the children or cat hadn’t kindly done for me, I went back to UCL. It was a relief to finish wandering around in the snow, but equally it felt strange to go back to my plush office, knowing that the occupants were stuck in their freezing and sometimes mouldy houses. Anyway, it was time to analyse the interview data. I had thought I would cringe at hearing my own voice on tape, mostly due to my accent going strangely northern when I talk to people whom my subconscious decides are less posh than I am, but that was nothing compared to some of the questions I had accidentally asked:

“So, is there anything else you do in your bedroom to keep warm?”

[occupant changes the subject]

A year later, insulation and double glazing had been installed in the houses, and it was time to do my study again. Maybe because it wasn’t so stressful the second time round, I noticed a lot of things on the estate I hadn’t paid attention to the previous year: the prevalence of pubs, off-licenses and betting shops as opposed to healthier activities like anywhere to have a cup of tea, the lack of employment and purpose amongst the youth, and how recent welfare changes were affecting the people on the estate. I decided I did not want to just come in as the researcher and take from them, by gathering data, then leaving – I wanted to give them something back. I tried to show interest in their lives and always ask about them and their families – but I gradually realised that the main thing I had given them was a sense of value when I asked them to be part of the study. One occupant even reported that nobody normally wanted to know him, never mind study him. They felt they were giving something by being part of the study, and in that they felt valued. This had the side-effect of changing my opinion on how we should do social action in our communities – by involving people and doing things together with them, as this makes them feel more valued than just doing something for them of which they are the passive recipient.

I took extra care to make my sensors cat-proof and dinosaur-proof this time, but something I couldn’t avoid was that three sets of tenants had moved out since the last time I was there. I wanted to re-recruit the new people in those houses to be part of the study. This time I didn’t use pity, but cheerleading. As I was explaining the study to one potential recruit, another of my tenants, an elderly gentleman, came bounding up behind me, dancing around and exclaiming, “They’re good sensors!” The man whose front door I was stood in front of ushered me in quickly and shut the door.

In conclusion, having tried it I would recommend the method of collecting both physical data from sensors and gaining the occupant view from interviews. I would also recommend people who work in or want to work in policy to go and spend some time with the people that the policies affect. It was really special to do something together with the tenants for a while, and I learned a lot from them. In the next post you can read about what I actually found out!