Is a heat pump really sustainable?

The sustainability of heat pumps and their reduction in the CO2 emissions depends largely on the source that drive them. For sustainable heat renewable electrification is essential.


That was what Scott McDonald, Director of Glasgow based research firm Sustain reported last Wednesday during the opening ceremony of the new trade fair Sustainable Heating at the NEC in Birmingham. He is optimistic about the growth of the share of solar energy, from the current 2 percent to 6 percent in 2020. “Within the solar energy market we see an exponential growth. It comes faster than expected, “says Mcdonald. But he also sees that engineers and scientists contradict each other on sustainable energy, allowing individuals and businesses delaying their buying decisions for solar panels or heat pumps.




Sustain launches the national heat pump trend report in the autumn, of which McDonald gives a sneak preview of the results. He presents a pie chart, which shows that 31% of the market thinks that it is good to have a heat pump with ample capacity. That’s a contradiction according to McDonald, because a heat pump has the best return on full load. “The workings of a heat pump differ from a central heating boiler, namely with negative pressure. Therefore it is better to have the required capacity of the heat pump not larger than necessary, “said McDonald.



Missed opportunity


McDonald reviewed various quotes from suppliers of heat pumps. “The offers are usually too long and way too technical, loosing the consumer along the way. “A missed opportunity, thinks McDonald. Is a heat pump sustainable? McDonald: “that depends on the CO2 emissionss just like with a central heating boilers. A heat pump with cylinder powered by electricity from the grid, emits per unit heat just as much CO2 as a gas-fired boiler. The CO2 emissions is only zero if the heat pump is powered completely by sustainable electricity.”




This implicates that the growth of sustainable heating goes hand in hand with the sustainability of the electricitty supply. According to Hall, there are several challenges to the market for renewable heating. “Firstly, the sector itself has to get the knowledge right. In addition to this, they need to share this information in a transparent way with individuals and businesses. Also the percentage of renewable electricity needs to be increased and the fluorinated refrigerants inside the heat pumps should be phased out.”


More wind and Sun


Mcddonald sees as final challenge that all the different techniques are complementary and don’t exclude one another. To further reduce the gas consumption in the built environment a large part of the buildings and homes need to be equipped with heat pumps. “That also means we will need wind and solar energy,” says Hall. He sees an annual doubling of the share of solar energy not as unrealistic. “It can go fast.”


First isolate


First step in the preservation of the heating supply according to McDonald is reducing the heat demand. “This can be done by fitting all properties with HR+/+ glass, extra roof insulation in half the homes and in two thirds of houses floor insulation. It is also necessary to put cavity wall insulation into one and a half million homes. “These measures will according to McDonald, lead to a reduction in gas consumption with four billion cubic meters and a CO2 reduction of over 7 Megatons. Total cost: 46 billion pounds.


Scenarios for heat pumps


McDonald outlines a scenario where all the houses are equipped with a heat pump. That leads to a 27.1 TWh higher electricity demand, but the gas demand decreases by 7 billion cubic meters. That means a CO2 reduction of 13.5 Megatons. Cost of the heat pumps: 69.7 billion pounds. A second (and more realistic) scenario assumes that half of all homes are equipped with heat pumps. This would result in a decline of 4 billion cubic metres of gas demand and would reduce CO2 emissions with 7 Megatons. The electricity demand will tthen rise with 16.25 TWh. The cost of this operation amounts to 35.5 billion pounds.


Photographer: Vincent Hartman