Tuesday, 16 June 2015

Moving into a home with low carbon energy? Do you know how to run it?

Over the last few years many new homes have been built with low carbon energy systems such as solar hot water panels, solar electricity panels, heat pumps, and ventilation systems with heat recovery. When you install these into an existing property you get instructions directly from the installer as to how to use them, but not if you are moving into a new property where they have already been installed. If the system is new to you - which they usually are - then it is unlikely that you will know how to operate it to its best effect. This means it won't reduce carbon emissions as much as it should and you as a home owner end up paying more for your energy bills than you might. It is a lose - lose situation: lose for you and lose for the environment. Sadly, research shows that this happens a lot.



This post is based on research by Lise Andreassen for her PhD at Royal Holloway University [1], London. She surveyed homes that were built in the London borough of Woking - various developments including flats and houses with a variety of different technologies installed. Between 2005 and 2012, Woking required all new homes built to meet 10% of their predicted energy demand with low or zero carbon technology (LZCT). That means equipment was installed - but it doesn't mean it was actually used in practice. 122 households took part in Lise's survey and she interviewed 26 in depth. The results were frankly shocking. Two of the householders did not even know what equipment they had, never mind how it worked or how to use it.

About a third of the households said that having the LZCT was a plus factor when selecting their home. However, another third of the households were not even told about it, or told too late to influence their choice. This suggests that estate agents do not believe that the presence of LZCT is a significant selling feature, even though it allows the new owners to save money on their energy bills.

Most of us are familiar with heating based on a gas or oil boiler and radiators. However LZCT systems differ from these in subtle ways, and it is important that householders are aware of these differences in order to run them optimally. For example, the most common LZCT was solar hot water panels. These are normally run in combination with a boiler or an immersion heater that brings the hot water tank up to temperature if necessary after the sun has done what it can. The worst possible configuration is to top-up the heat in the morning, so that when the solar panel is active the water is already hot. The top-up heater should only be used in the evening. However, more often that not the advice that was provided was the exact opposite 'one of the guys [from the developers] basically his recommendation was to run the electric heating, run the hot water heating for an hour in the morning, but then just see how it goes through the day....' A few interviewees had little faith in the people giving them advice 'And the developer didn’t really seem to know what was going on with the heating anyway. ... He didn’t seem like he had read the manuals. It seemed like he’d been given a set of instructions for showing us around ...’. Nor did the developers seem to have a very positive view on the technology themselves. For example, one interviewee was told that their solar hot water panels would provide 10% of their hot water overall through the year In fact they should be able to provide half or even more.

About half the householders said they were given sufficient information about the technology and the other half not. There were relatively few with no opinion on this. 61% of interviewees had looked at an instruction manual that was provided, but this was not always helpful. For example 'The instruction manual just tells you how to turn it on. It tells you how to turn it on; it tells you what the little meter inside means, that’s all.' This was for a solar hot water panel system so some hints about the top-up heater programming would have been very helpful but the instruction manual was only about the solar system itself, not how to use it. In other cases, the manual was simply incomprehensible. 'The manual that goes with [the ASHP] really is very, very unclear... Now, I’m used to reading instructions booklets because I was a science technician, [...] and I’ve tried several, several times and "What do they mean?"' One problem is that when the instructions provided are inadequate the householder may not realise this and look for other sources of information. It is hard to know what you should know if no-one has told you that you need to know it.

Verbal advice was very often of the form 'hands off, don't touch'. For example 'This is your [MVHR] system – doesn’t need touching, doesn’t need altering.’... And I said: ‘What’s that?’ and he said: ‘That is not to be touched.' This sort of advice discourages the householder from learning about the technology and how to use it effectively.

Another difficulty in many cases was the lack of feedback on how the system was operating, or difficult access to that feedback. For example, systems are often hidden away in cupboards so it is easy to forget they exist and need checking. I have written elsewhere on the need to make sure that solar hot water systems are functioning correctly. (See How much heat are you getting from your solar panels?). With MVHR (mechanical ventilation with heat recovery) there are very few controls beyond an on/off switch and sometimes a summer/winter mode. (In the summer, the heat recovery part is bypassed and the unit just supplies ventilation.) However MVHR systems do need their filters cleaned or changed regularly and this is easy to forget if the unit is not visible. '... the ventilation system feels like essentially a passive thing from my point of view, I just twist a knob ... You could argue that as you only have to do it twice a year that’s not a big hardship going up there, but I suppose people forget about it completely; whereas, maybe if you had it alongside the central heating control panel, they’d see it on a more general basis.’ It also makes it easy not to notice that the unit is not working at all. In one case the MVHR unit was in the attic and was switched off when the household moved in. Unaware of its existence, the householder had no idea it needed to be turned on.

There were also an alarming number of cases where the equipment was faulty. Of the 26 interviewees, one third reported faults that probably existed from the start. Solar hot water systems overheated - sometime to the extent that insulation was scorched off. In one case the the pressure vessel installed was the wrong kind and over time it deteriorated and burst. There was at least one case where an MVHR system leaked water because the pipework for the condensate had been punctured by a nail. A number of failures were due to inexperienced fitters. 'We’ve also had leaks. In fact, when they were finished restoring my panel, there were leaks so I had to get them back to do it up again. But at the end of the day, it seems to me that a lot of fitters haven’t quite got an understanding of what they are doing.’ Seven out of 19 developments had multiple households with faults. '... we thought we’d complain to the builders/developers, who brought in the experts, who then re-plumbed in, renewed and re-installed all 19 systems... Probably half a dozen at least, maybe more [were found to be faulty].'

It is not that surprising that householders often move in with inadequate documentation and/or faulty systems. This would not be so critical if householders already had sufficient general knowledge about the systems so that they knew what to expect. The key questions are:

  • What is it supposed to do?
  • How do I know it is working?
  • What do I need to do to configure it correctly? What else should I be doing or not doing?
  • Should it be making that noise?
  • What maintenance does it need?


There is little information along these lines already available on the internet. I did find Green Building Store has a useful FAQ on MVHR which covers some of these questions. However, I will see what I can do to fill in the gap - my first guide, for solar hot water panels, is on my website here.


[1] Domesticating low and zero carbon energy technology in new homes: pivotal events, determining configurations and influential feedback, a PhD thesis by Lise Andreassen for Royal Holloway University of London, 2014.

1 comment:

  1. Nicola,
    You can draw two contrasting conclusions from this work. 1) It's another example of the performance gap, and we must do better in terms of installation and education. 2) The home is not the place to install LZCT and that our love affair with decentralised energy has been a mistake.

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