European policy aims to reduce CO2 emissions of increasing the share of renewable energy based products and improving energy efficiency of heating and cooling systems in buildings. The Energy Efficiency Directive, which was approved by the European parliament, is expected to accelerate the development of energy saving products in Europe. Under this circumstance, HVAC industry suppliers have been looking at ways to enhance the efficiency of heating products and systems. Hybrid heat pump systems have been designed as one of the high energy efficiency solutions.
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Hybrid heat pump systems usually refer to a product or combination of products where two or more energy sources are connected together by means of intelligent controls.
Intelligent (smart) controls are the key to such systems:
- They manage the operation of the hybrid system and are most of the time integrated in the unit in packaged appliances. They can however be a separate part of the system in a modular appliance.
- Intelligent controls ensure the most efficient operation of the system (often resulting in minimum running cost) by means of choosing the least expensive energy and the mode of operation best suited to actual building needs.
- Intelligent controls can also be set up to optimise the use of primary energy in countries where legislation requires it for installation in the new build segment.
Currently available hybrid heat pump systems usually integrate heat pumps with a gas or oil condensing boiler or with a ventilation recovery system. Although systems where the heat pump is connected with a solar thermal circuit are also available on the market, they usually do not operate by means of intelligent controls.
Hybrid heat pump systems may be sold as one product in a single casing (packaged appliance) or as separate modules.
In both cases the heat pump will usually be equipped with the intelligent controls that will manage the system once the heat pump is connected to the boiler. However, in some cases the controller may be sold as a separate device.
Energy savings
Even though not many results of field trials are available at the current stage, the latest hybrid heat pump tests have shown that under mid-European climate conditions, the heat pump part of the system can cover 82 requirements over a year.
The boiler is mostly used during the coldest days - generally when temperature falls below 3°C or COP under 2.5. It also covers the extra heat needed to supply sanitary hot water as most heat pumps provide water with the temperature up to 50°C.
Market development
The Netherlands and Germany have been pioneers in introducing more efficient heating systems that integrate renewable sources with the condensing boiler in order to reduce energy use at household level and achieve European objectives of reducing the CO2 emissions.
Hybrid heat pumps were introduced to the UK market in 2011 and still account for a niche market of a couple of hundreds units.
In the UK hybrid heat pumps have been mostly (88 percent) installed in existing houses. They usually replace existing conventional gas boilers. Given the large base of such boilers installed in the UK (over 13mln units in 2010), the potential for growth of hybrid units, especially given continuous energy price increases, is high. The implementation of the Green Deal in 2012 might encourage end users to invest in more energy efficient homes.
However the UK market is very price driven and usually slow in adopting new technologies. Initial investment costs are much higher than those of gas condensing boilers, and there is very low product awareness. These are quoted as the main disincentives.
Through the RHI (Renewable Heat Incentive) scheme, the UK government is planning to incentivise the sales of renewable technologies in the domestic segment, but there is no mention of supporting hybrid systems in the current proposition of the RHI Phase II program.
RHI in its current form of feed-in tariffs expects the end user to carry out the initial purchase and installation cost of the system. With challenging conditions in the UK economy and no imminent change in view, this will almost certainly have a negative effect on the market uptake. With no financial support for hybrid heat pumps, BSRIA’s sales forecast for this technology does not exceed 120,000 units between 2012 and 2020.
Krystyna Dawson MA is a senior manager, Heating Special Projects, in BSRIA’s Worldwide Market Intelligence.