Thursday, 30 April 2015

Infra red heating panels - fantastic or fantasy?

There are many websites claiming, or at least suggesting, fantastic savings on your heating bills by switching to using electric infrared heating panels rather than conventional radiators. For example 'Tests have shown that by installing infra red panels, heating cost can be reduced by 70% when compared to centralised heating systems' [1]. 'Up to 50% cheaper than conventional gas central heating' [2]. Are these plausible? My investigations started when I was asked to comment on the claims on one particular site which said 'we expect you to save at least 50% on your energy bills and in some case[sic] up to 85% or more'. This text isn't there any more because I complained to the Advertising Standards Authority (ASA) about it, and the company (Logicor Ltd) agreed informally to withdraw the claims from its website. However, since then I have found this company is only one of many with similar products and claims and I despair of reporting them all.



Radiant heating is a Green Deal measure for warehouses and industrial premises.
Most reputable energy saving heating measures are supported under the Green Deal. Of course getting your measure approved requires a lot of expensive testing and just because a product is not approved does not necessarily mean that it isn't any use. It turns out that 'radiant heating' is eligible, though only for commercial installations, not domestic. The systems approved are fuelled by gas, not electricity, and are suited to 'large warehouses and industrial premises with high ceilings that are well ventilated'[3]. I don't live in a converted warehouse, and I don't suppose you do either. Also, there is an important distinction between 'radiant' heating and 'infra red' heating. Infra red radiation is not visible, by definition. So if it is hot enough to glow then it is radiant but not infra red.

Claims of energy savings for homes were withdrawn on the websites I complained about.
My investigations began with claims on the sites http://www.clear-heater.co.uk/ and http://www.intelligentheatingsystem.co.uk. They both cited a report, wholly funded by Logicor (Group) Ltd, written by a Dr. John Paul Gosling who turned out to be a a statistician at Leeds University. This showed that the panels could heat homes using 40-80% less energy than would be expected. I dare say the mathematics in the report is sound, but when I thought about it I realised that the results of the analysis were entirely irrelevant.* When approached by the ASA, Logicor said that their claims were not based on the Gosling report at all but on real customer data. I have not seen the latter but it seems it did not convince the ASA. Both those websites have now been updated to remove the ridiculous claims.

Dr.-Ing Peter Kosack objects to his research being 'misused by frivolous sales people'
So far so good. Then a friend pointed me to another similar site. In this case they cited a report [4] from a German Doctor of Engineering called Peter Kosack. I have found seven different websites all referring to this one piece of research that finds big savings from infra red heating panels compared to gas central heating. Peter Kosack is not pleased about this at all. He says (Translated from [5])

We have firm reasons to advise that the research results and other information on this internet site have been misused by frivolous sales persons of electric heating, for advertising purposes. It has often been falsely claimed by these people that they work with us. In particular, it is (falsely) claimed that the said products come from the infrared radiators that have been tested by the TU-Kaiserlautern.
...

The term 'infra-red radiator' has been defined (as yet) only for relevant high temperature infra-red radiators. .... According to the results of this research, it seems that more than 90% of the products offered as infra-red heaters are actually no such thing, rather, they are conventional electric convection (or) radiant heaters.

Kosack defines heaters as infra red if they transfer heat mainly by radiation rather than convection and that radiation is in particular band of wavelengths that is not absorbed by the air. Infra red heaters have to be large and flat with a surface temperature of at least 60C. Higher temperatures shift the balance more to radiation rather than convection - but would also present a considerable risk of burning in case you touch them. Below 60C convection tends to dominate. Traditional central heating radiators run at temperatures around 60C to 70C but they are shaped to encourage convection. Also traditional radiators are often partially enclosed to prevent accidents, especially in places where there are children or vulnerable adults present.

One test case found energy savings of 60% - but one test case is not enough.
Kosack's report describes an experiment performed on a single house in Germany, split into 2 flats. One flat was converted to use infra red panels, and the energy use for those compared with the other flat that still retained the gas central heating system. Over the whole heating season the infra red panels required 60% less energy that the gas central heating system did, when adjusted to energy per unit floor area. I have a number of reservations about the way the experiment was conducted, but even if I did not, and even if I was convinced that the heating panels on offer were functionally similar to the ones that Kosack used in his experiment, it would take more than one test case to convince me of such savings.

Other research suggests more modest savings.
Kosack is not the only researcher in this area. The Funky Heat website quotes from a number of articles in respectable journals that also suggest savings, but not of this magnitude. For example, the first two suggest that convection heating requires 30-35% more energy. That implies energy savings of about 25%.

Switching to electricity can cost you more, even when using less energy.
You need to be really careful, though, when looking at these claims to distinguish energy savings from cost savings. Electricity costs about three times as much as gas for the same energy (kWh) and all the infrared panel heaters I have seen are electric. Switching from gas heating to an electric system that saves 60% in energy would actually cost you 20% more to run. The first claim in this post was for cost savings of up to 70%. Now that claim was in comparison with 'centralised heating systems', not necessarily gas. A cost saving of 70% while switching from gas to electric implies an energy saving of 90%. I think that's pure fantasy.


* The report compared heat loss calculated from predictive models with actual energy use by the panels. The 'savings' indicate that either the heat loss calculations were based on inaccurate data, or that other sources of heat were supplementing the panels. The latter was certainly the case, as the analysis admitted that internal heat gains were ignored. For the moment you can find the report here. but I would not be surprised if it disappeared soon.

[1] Infra red Heating Panels (www.abbeysolar.com) Accessed 29/Apr/2015
[2] Healthy Heat - Technology (www.healthy-heat.com) Accessed 29/Apr/2015
[3] Information for the supply chain on Green Deal Measures (www.gov.uk) Jan 2013
[4] Dr.-Ing. Peter Kosack, Report on the research project "“Case Study of the Differences between Infrared Heating and Gas Heating in Old Residential Buildings, Using Comparative Measurements (2009) (This is one translation of the original German manuscript. There seem to be a number of other translations from various sources).
[5] PROJEKT-HOMEPAGE DR.-ING. PETER KOSACK (http://www-user.rhrk.uni-kl.de/)

4 comments:

  1. Great piece. And let's not forget the higher carbon emissions from electric heating - currently two-and-a-half times those for gas in the UK, which means you'd need an efficiency improvement of at least 60% to justify switching from gas to electric heating on climate change grounds.

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  2. This comment has been removed by a blog administrator.

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  3. If you have installed Clear Heating and have issues join us at
    https://www.facebook.com/groups/178320522678408/

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  4. Maybe there is a use for IR panels after all. This article points out that IR has an advantage in draughty, poorly insulated homes because it doesn't heat the air that is about to leak out anyway. In a well insulated airtight home, the air will heat up from the furniture etc. but in a leaky home that can't happen.

    http://www.yougen.co.uk/blog-entry/2867/Are+Infrared+panel+heaters+a+good+way+to+heat+a+room'3F/

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