AIR CONDITIONING
The benefits of heat pumps and good ventilation
Jason Tinsley, applied product manager at Pacair discusses the evolution and importance of VRF systems in terms of managing indoor air quality.
B
ack in the early 1990’s, the UK HVAC market started to change as two new product ranges from Japan entered the UK
market.
VRF (variable refrigerant flow) air conditioning systems made a fairly quiet entrance into a market sector that was heavily dominated by 2- or 4-pipe fan coils served by chillers and gas boilers.
Little did we know at the time that VRF would go on to become a main stream solution for most consultants and installers. So why did it happen? In a word, flexibility. Initially there were only a few outdoor unit models available but the ranges soon expanded with demand for larger capacity outdoor units as well as an extended range of indoor units. The main game changer was the introduction of the heat recovery VRF outdoor units.
The fact that you could have one outdoor unit that could simultaneously heat and cool various fan coils was a real innovation. At a stroke it enabled a design flexibility previously unheard of
28 February 2021
and it still continues to do so. Today’s building designers and consultants
have to consider more carefully how they efficiently provide heating, cooling and hot water to their buildings in order to comply with building regulations. Compliance is done through either Standard Building Energy Modeling (SBEM) which is used for commercial buildings for Part L approval and Energy Performance Certificates – or Standard Assessment Procedure (SAP) for domestic buildings. One of the big benefits of heat pumps is that although they are already highly efficient in in terms of how they heat either air or water they also automatically benefit from the rapidly reducing electrical grid emissions factors in SAP. Under the new SAP10 electrically related carbon emissions have reduced significantly from 0.519kgCO2
/kWh down to 0.233 CO2 /kWh with
SAP10.1 looking likely to settle on 0.136kgCO2 kWh.
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As the UK continues to clean up the national electricity grid with the introduction of more wind, solar, tidal and nuclear generation these
emissions factors are only going to reduce further over time. What this means is that heat pumps will continuing to benefit from this and displace other technologies such as gas boilers for heating and hot water and CHP as they no longer become a viable option under new and future building regulations. Other key local plans such as The London
Plan also promote the use of heat pumps for heating and hot water as they significant reduce CO2
emissions compared to other methods of
heating such as gas boilers. Air-to-water or water-to-water heat pumps suit a wide range of property types from single dwellings up to large multi apartment buildings. Heat pumps can now offer a wide range of water flow temperatures depending on the refrigerant being used. Typically R407C systems can provide water at up to 70°C, R410A up to 65°C and heat pumps using CO2
up to 90°C depending on manufacturer.
Over the last 10 years or so air-to-water heat pumps which have gained significant traction in both the domestic and commercial sectors with
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