Heat pumps are playing an increasingly important part in the modernisation of both commercial and residential buildings. Scott Gleed, chairman of the B&ES Refrigeration, Air Conditioning and Heat Pump group, explains why.
There are somewhere between 60,000 and 80,000 heat pumps installed and working in commercial buildings – the market has been growing steadily at around five per cent a year since the mid-90s. On the domestic side, the government expects the market to reach 200,000 per annum on the back of a major push for renewable and low carbon technologies, including funding from the Renewable Heat Incentive (RHI).
That is because heat pumps are the most efficient choice for many applications, including small to medium sized air conditioning and domestic/light commercial heating. While the central heating boiler market fell by around 10 per cent in 2012 sales of air to water and ground to water heat pumps has continued to grow. In many cases, they are seen as an ideal alternative to the traditional gas-fired boiler and can deliver carbon savings of between 20 and 30 per cent compared with an A rated boiler if sized, installed and commissioned properly.
As more of our electricity starts to come from low carbon sources, so the case for heat pumps will strengthen again. The more widespread use of lower temperature heating systems, such as underfloor, is another positive development for heat pumps, which naturally produce heat at lower temperatures. The push for more energy efficient heating solutions that are also more discreet i.e. with fewer obvious heat emitters like radiators; make heat pumps an increasingly desirable option for system designers, specifiers and the discerning end user.
Air-to-air heat pumps offer excellent close control to maintain day and night time temperatures. They are also relatively easy to install and do not require large amounts of space in or around the property. The availability of multi-split options, with one outdoor unit serving up to four indoor units, that deliver heating in the winter and cooling in the summer, makes them ideal for a wide range of UK homes.
Ground source types (GSHPs) are a more complex case. They can produce even better coefficients of performance (COPs) of up to 4.5 depending on the flow temperatures achieved. However, they are not a cheap option and so the installer has to thoroughly research the project in hand to make sure the investment can be justified.
They are ideal for new build projects, where the necessary ground works can be carried out as part of the initial foundation and site clearance schedule. There also needs to be sufficient space to accommodate either boreholes, ideally able to go down to a depth of 100 metres, or ‘slinky’ tubes to extract the latent heat from the ground buried at around 1.2 metres below the surface, but spread across a considerable area – sometimes up to ten times the floor area of the building itself.
They are an expensive, but highly efficient and reliable source of renewable heat. However, the development of the heat pump market has not been plain sailing. The Energy Saving Trust’s report ‘Getting Warmer’ was pretty damning and led to air source heat pumps (ASHPs) missing out on the first round of funding under the RHI.
A coefficient of performance (CoP) of 3 or above is seen as a realistic efficiency benchmark for a quality ASHP installation – three units of power out for every one of primary energy used. Sadly, only 13 per cent of the systems analysed by the EST over a year reached that level. The research did not find any fundamental problem with the technology, however. Rather, they put the poor result down to problems with installation, controls, commissioning and user behaviour.
“The best performing systems show that well-designed and installed heat pumps can operate well in the UK,” the report said. However, it pointed out that “performance can vary considerably from one installation to another”.
Improving the quality of installation and, particularly, final commissioning must be a major priority for our industry. We are improving as we gain more experience of the technology. We also need to get better at explaining our work to our customers so they don’t have problems understanding and operating the systems – and end users should be prepared to challenge their installers to make sure they are given all the necessary information. This is an ‘emerging’ technology and users cannot expect it to work like a conventional heating or cooling system.
It is also important to be aware of relevant legislation and to recognise the particular challenges of projects that involve refrigerant gas. In particular, the F-Gas regulation, which was established across Europe to reduce the leakage rates of refrigerant gases that will cause harm to the atmosphere if they escape from the system. It is an important piece of legislation and it has already had a discernible impact on the freedom of unregulated and untrained installers.
If a heat pump has to be installed on site, with refrigerant pipes between indoor and outdoor units to complete the refrigerant circuit, the installing company must be certified by REFCOM, or a similar refrigerant certification body, and the engineer trained in compliance with the F-Gas legislation. B&ES member firms are intent on complying with these rules as we recognise this is for the benefit of the whole sector and our customers.
Full compliance with the F Gas Regulation is also required when servicing or de-commissioning any type of heat pump to prevent accidental loss of refrigerant charge by non-qualified personnel. If the system is of the single unit ‘monoblock’ type, there is no need for any F-Gas works on site as the installing operative simply places the unit ready to be connected to the electrical supply and the flow and return heating water pipes, however there is still the need to use a qualified operative for servicing and decommissioning work.
The RHI could have a big impact on the growth of the heat pump market. Unfortunately, only ground and water source heat pumps were initially included, but hopefully by the time you are reading this air-to-water and air-to-air systems have been brought into the fold as these have, arguably, the greatest market potential.
To receive RHI payments, however, systems will have to perform as designed and the lessons of the EST trials will have to be learned. It might be politically expedient for the government to trumpet its record of supporting energy saving technologies, but simply installing heat pumps is not enough. If they are not properly designed, installed and commissioned correctly they will not deliver the expected savings.
The thermodynamic principles associated with heat pump technology are closely aligned with those relating to traditional heating, refrigeration and air conditioning systems, so many of the relevant skills and expertise already exist within the building engineering services industry.
However, the important message to get over to end clients –whether domestic or commercial – is that properly trained, multi-skilled engineers are vital to their ambitions for reducing the carbon footprints of their buildings and there are additional aspects of heat pump systems that require special training. Installers must also be members of the Microgeneration Certification Scheme (MCS) for their customers to receive RHI payments.
It is also crucial that installers prepare thoroughly before any heat pump project to ensure the right type and capacity of unit is selected and also that local site conditions are taken into account before starting work. Commissioning is also very important. Heat pumps need to be adjusted and tested once in place to ensure they are performing as intended. Squeezing commissioning time can lead to disaster as the EST report showed. Integrating a renewable system into an existing building with conventional services can be particularly tricky so requires expertise and time.
There are still, clearly, some major issues to be ironed out before the UK heat pump market can start to realise its full potential. For example, our elderly housing stock suffers from poor insulation standards that work against heat pump efficiencies. However, as improved insulation and double glazing is addressed by the Green Deal, which comes into effect in October 2012, so the picture for heat pumps will also improve. With the right additional training to supplement their already proven thermodynamic engineering skills, building engineer services contractors can help make the government’s predictions for heat pump market growth and energy savings come true.
Air conditioning inspections
Only a small percentage of air conditioning systems have been inspected despite rules existing since 2008 to cover this area. The Energy Performance of Buildings Directive (EPBD) was recast in 2012 and now contains a legal requirement to lodge the inspection reports on the national register, but there has been very little evidence of an upturn in activity in this area.
It makes good sense to reduce the burden on business and too much regulation is a bad thing, but when you do have targeted legislation in place it should be enforced and local authority officials must be resourced to make sure they can enforce it. This requirement is also for the benefit of building owners as it can help to reduce their running costs.
Owners or operators of buildings are required to have any air conditioning systems with a rated maximum output greater than 12kW inspected. This regime is (in theory) policed by Trading Standards on behalf of the Department for Communities and Local Government, “but it is clear that little or no enforcement is in fact taking place” said Scott Gleed, and DCLG is not even able to confirm how many inspections have been undertaken to date.
B&ES subsidiary BESCA (www.besca.org.uk) set up an accreditation scheme for inspectors in 2009 because we recognised what an important issue this could be for building owners and operators, who must have faith in the competence of the people carrying out their inspection. This is a legal requirement of which all building clients should be aware and the introduction of mandatory lodgement at least means that the authorities now have a better idea of how many inspections have been carried out.
This is not just a bureaucratic exercise, but a genuine attempt to improve the energy performance of air conditioning systems across the country for the benefit of our collective carbon footprint and to reduce running costs for all air conditioning users. Air conditioning users should look on this exercise as ‘free consultancy’ because the inspection will flag up any poor performance issues and suggest methods for putting it right. With electricity costs still on the rise, that could turn out to be a valuable business investment.
The process might seem like an irritating box ticking exercise, but it could have big implications for electricity consumption across the whole UK building stock.