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 3 (does behaviour matter?)

Jenny Love, UCL Energy Institute

Now, I realise that taken out of context the title of this post might be interpreted as, “Dr. Love will now answer your relationship questions”. Please don’t write to me with your relationship problems – I won’t be able to help unless they can be solved by building physics.

The title is actually referring to the implications of the previous post here, about the fact that when dwellings undergo energy efficient retrofit (e.g. insulation, double glazing), the outcome which arises is partly dependent on how the occupant reacts. I found some occupants who kept their home colder afterwards; I found others who for various reasons increased their use of heating and made their home much warmer. I couldn’t have predicted which occupants would do what.

This post is the ‘so what?’ question: does it really matter that occupants react to retrofit in different ways? What effect does this variation in behaviour have on their energy use?

I am going to explain the answer through the medium of cheese.


Now, that’s not entirely helpful in its current form: why this answer, and why the cheese?

  1. A model

When you’re trying to speculate on the value of something you can’t measure, you can use a computer model. For example, I wanted to know what the energy use of a household would be, at all different levels of insulation (a physical variable), and at all different levels of how much the occupants have the heating on (a behavioural variable). I couldn’t go and measure the same house with various different levels of insulation and various different types of behaviour, so I simulated it in a program called EnergyPlus.

  1. The results

After going to all the effort of learning EnergyPlus and working out how to assemble the results on a graph, all of which involved some near-all-nighters, a lot of tea and a significant quantity of Maltesers, I was rather disappointed to see that I had in fact produced….

…a large piece of cheese.

Let me explain. By the way, if you hate graphs, you can at this point skip to the summary.


The cheese shows energy use plotted against heat loss of the building, at different types of occupant heating behaviour. It is marked out by a blue line at the bottom and a red line at the top. The blue line is the relationship between energy use and the leakiness of the house for the situation where the occupants have the heating on as little as is realistic: one hour per day, only at 16 degrees C, only heating one room. If their house is leaky, they end up using more energy, but the relationship is not very steep.

The red line is the situation where the occupants have the heating on as much as possible: 24 hours a day, at 23 degrees C, all rooms of the house. You can see that the relationship is very steep: if the house is leaky, they use a lot more energy.

Since the blue and red lines mark out the extremes, everything within the cheese in between them represents possible energy use at possible types of heating behaviour. The green line in the middle, for example, represents people who have the heating on for 9 hours per day, in some rooms, to 20 degrees C: a sort of medium scenario.

Retrofit is moving from the right of the cheese, to the left. How far you go represents how ‘deep’ the retrofit is – how much more efficient the building is made.

Example 1. Shallow retrofit, no behaviour change

The type of houses I monitored started out where the pink dot is on the picture below. That is, they were very leaky and they weren’t using the heating very much. Let’s say that one of those houses then had the type of retrofit which really occurred on this estate (‘shallow’), and the occupant didn’t change their use of heating at all afterwards. The arrow represents how the house would move through the cheese. You can see that slightly less energy is used after retrofit.

cheese graph shallow no behaviour change

Example 2: shallow retrofit + behaviour change

This time, imagine the occupants do change their use of heating after retrofit. I saw people changing their behaviour in a variety of ways, so this can happen. In this picture it’s taken to the extreme – all possible changes in behaviour are shown.

cheese graph shallow behaviour change

There is a massive variation in energy use after retrofit resulting from this. Energy use could go down or up quite a lot. We might think it’s quite unlikely that after retrofit people use more energy than before, but I saw it happen in my small sample. Furthermore,  when new people move into the house their comfort standards might be a lot higher than the old occupants. I  saw this happen in my sample too, as some of the post-retrofit occupants had a baby and so had put the thermostat to 28 degrees C!

Example 3. Deep retrofit, behaviour change

cheese graph deep behaviour change

This time, imagine the houses start leaky and are made extremely efficient. The same variety of change in occupant heating behaviour – people going from the start point down to the blue line and up to the red line – as in the last graph, is plotted on. But this time, look at what happens to energy use. Whatever the occupants do – however they change their behaviour after retrofit – the resulting variation in energy use is very small. That is, in very efficient houses, whatever the occupants do with the heating doesn’t have much effect on energy use. That means it’s easier to predict the energy use after retrofit, and occupants can live in a warm house and still save energy, without us having to tell them what to do or trying to change their behaviour.


What I am arguing for, through the use of cheese, is that if we only have one chance to retrofit a building, we should do it deeply – put a lot of insulation on, treat all the places it loses heat – as opposed to ‘shallow’ retrofit – what the current policies are leading to in social housing. It is important that energy use decreases after retrofit whatever the behaviour of the occupants who live there through the retrofit, and whatever the behaviour of the the next ones who move in. I did see people increase their use of heating after retrofit, and I also saw new people who moved in and used heating more than the previous ones, and it is important that these actions still result in lower energy use than before.

I hope the cheese made sense to you. Any questions, feel free to ask – although  the invitation to ‘Ask Dr. Love’ applies strictly to energy and buildings…


1. There are many caveats to this work, and in applying the use of a ‘model’ to real buildings. I didn’t go into them here – this is a conceptual argument and not absolute truth.

2. For those who love graphs, you can find a more academic version of this argument here. Not for the faint-hearted.

3. I should say thanks to two very clever people: Tadj Oreszczyn and Andrew Smith (aka my supervisors), for helping me interpret the cheese graph and its five-dimensional counterpart which appears in my thesis.

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!


Time to find out about heat pumps…

Jenny Love, UCL Energy Institute

I’ve been spending the last 3 months working on domestic heat pumps –  major players in the debate about future heating for the UK –  but whilst trying to converse with my family about this over Christmas, it became clear that they had no idea what I was talking about.  So I’ve decided it’s about time to make heat pumps known. This article is based around some of the questions you might ask if you’ve never heard of a heat pump and don’t have an unhealthy obsession with thermodynamics. It’s always good to be able to impress your friends or potential mate by pointing out a heat pump when you see one:

air source heat pump

(source of photo:

1)      What the heck is a heat pump?

Normally in Britain you heat your house by switching on your boiler, which burns gas, heats water, and sends it to your radiators. The source of heat is the chemical energy in natural gas. Now, gas may or may not be around to stay – if it is it will only get more expensive – so there is talk about whether electricity will replace gas for heating homes. Electricity is normally made in a power station from heat, a process which loses a lot of energy, so putting the effort in to make electricity only to transport it along a wire and turn it back into heat for your house is quite wasteful. But a better thing you can do with electricity is move heat which already exists – I don’t just mean from one physical location (like the ground) to another (your house) – I also mean from one temperature (cool ground temperature) to another (warm living room temperature).

A heat pump uses electricity to move heat from a cool place to a warm one. When I first heard about this I thought it must be some kind of miracle, but then someone pointed out that that’s how a fridge works (electricity is used to move cold heat from inside the fridge to the warmer exterior, keeping your fridge cool).

Why would you do this – well, if you do the physics, you can work out that putting in a bit of electricity can move a lot of heat (about one unit of electricity can put 3 units of heat in your house), meaning that the energy use from heating your house with a heat pump should be much lower than that from using a normal boiler.

Now, you may not have heard of one of these devices, but David Mackay, the chief scientific advisor at the Department of Energy and Climate Change, recently gave a lecture (at this event: in which he foresaw 20 million of them installed in homes by 2050 (almost one in every property). So maybe it’s time to find out more about them…

2)     In what ways is using a heat pump different from how I normally heat my home?

Heat pumps  work best when the temperature difference between the heat’s original location (e.g. the ground) and its end location (e.g. the living room) is low. This normally translates to the temperature of the thing in the room which is going to give you heat (called the ‘emitter’ – e.g. a radiator) not being as high as we’re used to. Here are a few consequences of this that you might find strange:

a)      Heat pumps work best with underfloor heating instead of radiators.

If the temperature of the emitter is low (e.g. 30 degrees C), you need a high area of emitter to give out enough heat. For example, the area of the floor of the room. It would be silly to have a radiator this big so underfloor heating is often used.

b)      They work best if you have them on all the time.

If the temperature of the heat delivered to the space is low, you can’t get enough heat out if you just have the system on for a bit in the morning and a bit in the evening. Having the heat pump on all the time is something that we’re not used to but is necessary for the right amount of heat, delivered at a low temperature.

c)       They are very easy to operate sub-optimally

Take a normal condensing boiler. Its efficiency (see below for a definition) is probably around 83% whether it is on for a long time, a short time, whatever the temperature settings on it, however it is installed in a property. Boilers are relatively robust against variation in operating conditions. Heat pumps, however, are a very different kettle of fish. If any part of it (e.g. the hole in the ground, the compressor, etc..) is too small, it can’t provide enough heat and a backup electric (i.e. wasteful) heater comes on. If it is too large, firstly it might suck too much heat out of the ground and freeze it; secondly it might switch off and on quite a lot – if it does this more  than once every six minutes ( then this is detrimental to its performance. There are lots of things to set correctly: pump speeds, temperatures in the system such as water flowing around to the emitters, the way it ramps down when the weather outside it warmer (called ‘weather compensation’) and plenty more. The thing is, you probably won’t know whether it is working optimally or not. I would like to see a heat pump which monitors itself as a whole system and tells you that kind of thing.

3)      Do heat pumps actually work, and how would I know?

Efficiency, or performance, of a heating technology is generally defined by heat it provides / energy you put in. This is the source of the 83% mentioned in section 2 (from this report: Now, to measure this, there are two kinds of test. Firstly, lab tests: those done by the manufacturer which say, “oh look, you put one unit of electricity in and move five units of heat to your house, that’s lovely”; secondly, those which are done in real houses with real occupants. The latter are known as ‘field trials’ and have been carried out in the UK – you can read about them here:

or if you are quite used to scientific reports then here:

The moral of the story is that, of course, heat pumps do not work in-situ as well as in the manufacturer’s lab (like anything really), but that they can work well:

–          It has been shown that the whole system is extremely important. To work well, everything about them has to be done correctly: the sizing of the pipes which are buried underground to pick up heat (the ‘ground loop’), the sizing of the actual heat pump box, the insulation of the pipework going into the house, the various temperatures in the system…

–          There is a way of measuring this overall success as opposed to that from lab conditions – it is called the seasonal performance factor. It’s quite simple really – you measure the heat delivered by your heat pump to your rooms/the hot water, and divide it by the electricity the heat pump uses. You’re looking for an answer of at least 3, really, for it to be worth it. The SPF is what the aforementioned field trials were trying to measure. That’s what you should ask the manufacturer about.

4)      When is a good time to buy a heat pump?

In my field, we have a saying: ‘Fabric first’. What we are talking about is this: when you take a building and want to make it energy efficient, the most cost-effective thing to do first is to reduce its heat loss, by insulating the building fabric, sealing up gaps, getting rid of cold bridges, etc. Then only when you have done that should you consider changing the heating system, which will cost you a bit more for the same amount of carbon savings (after that, it’s time to think about fixing solar panels onto your roof). The reason some people do it the other way round is that solar panels are more sexy than boilers, which are more sexy than insulation. (Guess what my PhD is about: insulation.)

scale of sexiness

(image sources:,  my PhD fieldwork)

But in our field we always advise making our house more airtight and better insulated before considering getting a heat pump. There’s a good reason for this: as I mentioned earlier, heat pumps work best when they’re on all the time. If you have a leaky building, then you’re constantly going to be putting heat in, which is constantly being lost to the outside. Bit of a waste.

But if your house is quite well-sealed, then NOW is a good time to buy a heat pump. If you’re quick, there’s currently a discount from the government’s Renewable Heat Premium Payment scheme:

And then later on the Renewable Heat Incentive’s domestic scheme will be launched:

However, it is not yet the best time to install a heat pump in terms of CO2 emissions. If you are on normal grid electricity, and your heat pump performs well, it will cause less emissions than a condensing boiler; if it doesn’t then it may well not. This is because grid electricity is still pretty high in carbon. If you choose a renewable tariff, you can avoid this, but otherwise you may have to wait until renewable generation is a higher proportion of the UK’s energy mix.

5)      Is it possible to be a bit too excited by heat pumps?

It is, yes. The best example I’ve found of this is the following three minutes of video captured excitedly by a phone camera of a heat pump in defrost mode:

I’ll leave you with that…

Energy use in a shared office: who is responsible?

                                                            Faye Wade & Jenny Love, UCL Energy Institute

We decided to write this article because this is a tough question that not many people talk about. Our department, UCL Energy Institute, moved into a refurbished office about a year ago, and a couple of research projects have been following the refurbishment process. Therefore we will use a combination of our experiences and the way things are generally done to talk about the main things that influence office energy consumption and whether there’s anything you as a building user can do if you’re stuck with an energy-inefficient office. In this article we assume that you’re an employee, as opposed to a cleaner or building manager.

1.  Who is involved in setting up and using an office?

To the left is a very simplified version of how an office comes into utilisation. In reality, such a diagram might look more like spaghetti than a linear process; we’ve made it more straightforward so as not to frighten anyone. We just wanted to show that before occupation, decisions have already been made by various parties about the nature of the heating, air conditioning, lighting and other energy-consuming installations. Any design and installation decisions made at this stage should make sure that the building will comply with the minimum efficiency standards given in the Building Regulations but don’t assume that they have been! It is only the building owner or occupier who (potentially) worries about the energy bills, or in your case the billing might fall on whoever manages each floor.

In terms of what actually gets put in, very rarely do the future occupants get consulted even though they will be the users. It didn’t even happen in our case – and we study energy in buildings for a living!

The handover stage, and commissioning, could both be valuable opportunities for the building owner or occupier to raise concerns about the installed systems, for example how they are controlled and their energy consumption. However, this process still doesn’t necessarily involve those that will actually use the building.  In our case, we just moved in and started working. For us, commissioning happened in several stages, with the building managers having to address several snags and missing bits here and there. In other words, there are lots of defaults set before occupation which, if not challenged, could result in high energy consumption.

We have been lucky enough to be able to provide feedback to our building owners and managers. A couple of members of the Energy Institute researched the lighting and the heating from energy use and occupant satisfaction perspectives and have been able to relay the results and suggested improvements to the building managers. An example is that originally the lights in the office came on automatically, regardless of whether they were needed, Faye raised concerns about this after commissioning and now we’ve got that changed, hopefully saving some energy. As part of a ‘living lab’ we are also getting some smart meters installed so that we can really keep track of our energy use.

But let’s assume that you’re not in the middle of a refurbishment and are set in the ‘occupation and maintenance’ stage. Let’s look at the different types of building ‘user’ in more detail, suggesting how they might influence energy use and how you as a tenant might be able to change things…

2.  More on the occupants

The boss: If you are a boss, you might be subconsciously influencing your employees’ energy behaviour. Jenny once worked in an office of a sustainability consultancy where, to decide whether it was acceptable to switch the air conditioning on, we went and had a peek in the boss’s office – and lo and behold, he had it on full blast. We advise bosses to use their influence for the benefit of energy saving, and to tell employees where he/she notices waste. We also appeal to you to communicate and represent employees in front of your boss (employees might not have access to building manager).

Visitors: People coming for meetings, etc, are also ‘users’ of the building, and even though it is unlikely that they can influence energy use, their view of the building might influence the bosses and building managers to take action. A big display energy certificate in the entrance makes sure everyone that comes in the building knows how it performs energy-wise. Also, as a visitor to other buildings you can have influence – my colleague who goes to the Institute of Physics a few times per year for meetings managed to get the wasteful halogen lighting in the lobby changed to LED lighting by sending several letters.

Cleaner and Security: What about people that come into the building after the 9-5 day is over? Even if you switch all the lights off, the cleaner might well come along and switch them all on again. We don’t think it’s part of current cleaner instruction to turn everything off. Could it be? And what about security? Do you have someone on site after hours that might be using additional energy? Are they using any required energy in the most efficient way possible?

Building Manager: The building manager decides how everything is run – this is the person controlling your building! If you’ve got problems with the building, this is the person you need to feed back to. Our building is one of many owned by UCL, and UCL Facilities and Estates manage it. We have a Building Management System (BMS) so Facilities and Estates can remotely control our systems; this is the same in many office buildings.

Employees (us!): Let’s face it: when it comes down to it, energy is used in offices so that we can do our work. The employees are the people that spend the most time in the building, so we can do the most to reduce its energy use, here are a few tips for how…

4.  What to do if you’re stuck with a sub-standard building

Now, you may have individual control, shared control or no control over certain energy services like lighting and heating…

Individual control

Even though you may think you have none of this, you probably do – for example, turn your computer off at the end of the day and disconnect other things on your desk like the phone, and if you have the guts, ask others to do the same.

Shared control

There are a few problems arising from shared controls, for example:

–          The ‘Everyone-leaves-it-to-everyone-else’ problem (this happened to us this week: I came into the Energy Institute on Monday morning to have someone tell me that the heating had been on all weekend)

–          The ‘peak-trough’ problem, which is as follows: Jenny wants the heating at 26 degrees, so turns the heating up to that. Faye comes past and prefers 18 degrees, so turns it down. Jenny turns it back up, perhaps because she is in a bad mood from excessive programming and wants to exert authority over the office. Faye turns it down. Hence, the system has to work harder.

Our solution, simple as it sounds, is not done very often: talk between yourselves about shared preferences. Perhaps it is not done very often because people don’t want to challenge each other’s actions, opting instead for changing the settings themselves. Also, this could help the everyone-leaves-it-to-everyone-else problem as you could vocalise the perhaps-held assumption that the last person needs to turn the lights and the heating off!

No control

Many systems are flexible, e.g. lighting can be put on different settings such as: default on, default off, go off after 20 minutes of no occupation… It is the building manager who is in charge of these settings. However, if the occupants have no idea of the existence of the different settings or the identity of the building manager, they are thus unlikely to be able to ask for less energy-consuming settings. Your boss should know who the building manager is, so we advise getting the support of a little group of you then going to the boss to request access to the building manager, to see what can be done.

If you do have no control, that might be a contravention of the Building Regulations – did you know that the following exists in the Non-domestic Building Services Compilation Guide (2010 edition):

Be aware that something called “Post-Occupancy Evaluation (POE)” exists. Although it’s not regulation at the moment, some buildings undergo one.  It’s basically a way of finding out whether the building is performing as designed, in terms of usability, energy efficiency and a range of other indicators. More information here:

5.  Conclusion

Although you maybe weren’t involved in the design process or the running of the building, know that you can influence its energy consumption – it’s important to take actions as an individual, to talk about the energy consumption of your office as a group, and to try to influence key people like the boss, the cleaner and the building manager.

It would be great if you could post a comment about your situation, things you’ve tried, what has succeeded or failed…

Happy Green Office Week from both of us!