Ireland's only dedicated building services engineering journal
Ireland's only dedicated building services engineering journal

Heat Pumps — HPA’s Sherlock Argues Facts!

Richard Sherlock, Heat Pump Association (HPA) Director
Richard Sherlock, Heat Pump Association (HPA) Director

Previous comment — Once the heat pump wears out, my guess is that it will be replaced by a plug-in heater, let me suggest why. 

The HP market has grown in Ireland in response to DEAP and Part L 2011. At a BER of A3 or better, the space heat demand is so low that very little heat is required. The lifecycle cost of the HP cannot be justified in energy savings terms: the savings in energy or emissions do not justify the installation when compared with other heat sources

Reply — The heat pump market has grown for many reasons, not least the requirement for heat in buildings combined with the need for a reduction in the use of fuels such as kerosene for home heating. With over 1.5 million residential homes in Ireland, there is significant need for heat pumps in Ireland in the retrofit market.

In the new build market there will always be a heat load due to fabric losses … passive for all houses is not likely to happen in the near future (if ever). Also, ventilation losses need to be accounted for as these too have a running cost attached.

DEAP is a stylized version of a building, which takes average occupancy and makes many assumptions. It is fair to say it is hardly a living laboratory and should not be seen as such. While not intending to be critical of the Irish DEAP, the DEAP figures do not always reflect reality and should not be treated as an absolute.

For example, a C-rated house could be turned into an A-rated house purely by adding excessive PV panels though this would not be much good to the end-user who is buying oil for heating!! So not all A-rated houses are equal on running cost. DEAP does not account for running cost.

However, it does work on the basis of primary energy. It is primary energy use that we are trying to reduce overall and it must be reduced in the living real world now, and not at some future date. We must deal with today’s housing stock and building standards, and these are some of the valid reasons to install a heat pump today. A heat pump is the only heat source that is primary energy positive.

In fact, I am delighted to see heat loads reducing as this will reduce the capacity of heat pumps and thus the cost of the systems installed. All credit to the policy makers, engineers and architects for making these lower heat loads a reality for heating suppliers.

Previous comment — Compare a HP for a semi-detached house with a BER of A2 against a 2kW plug-in heater and a night rate immersion. The capital cost of each is (in order of magnitude terms) €200 for the heaters versus €10,000 for the HP. 

Reply — Comparison on a fair basis is everything in this debate. Each case must be looked at individually and not in a “broad brush” manner with indicative high prices of €10,000.

Let’s compare a HP for a semi-detached house with a BER of A2 against a 2kW plug-in heater and a night-rate immersion. The capital cost of each is (in order of magnitude terms) €200 for the heaters versus €10,000 for the HP, as per a previous contributor.

It is unclear where this cost comes from and, in the absence of some basic facts such as the size and heat load of the house being referred to, it would be hard for me to accurately cost.

However, I assume that the immersion referred to will be thermo siphon as the cost could not reflect the price of an energy efficient pump as required by European Energy Efficiency Legislation.  Perhaps this cost is not all-inclusive and the heat pump is not €10,000. In any case, with a primary energy factor for electricity in excess of 2.4 an immersion significantly increases the primary energy use and the suggestion of using the immersion rather than a heat pump runs contrary to energy conservation.

Previous comment — The only real justification for the HP is the requirement for compliance in DEAP for CO2 emissions, which is based mainly on the primary energy factor applied to mains electricity. This CPC requirement does not exist in a retrofit situation. 

Reply —  This is simply not true. Again it is worth reiterating that a heat pump is primary energy positive. In a retrofit situation huge primary energy gains can be made by using a heat pump as opposed to a boiler, and certainly against an immersion. It is fanciful to proceed with energy policy without trying to reduce the consumption of high carbon energy fuels such as kerosene.

Couple this with a primary energy factor of less than 90% for a boiler and the argument in retrofit situations for a heat pump is more than convincing. The same argument also holds true for the vast majority of new builds.

Heat pumps were offering real-value propositions long before the introduction of DEAP and trying to justify their only function as you have described is not credible and is unfounded.

Previous comment — In, say, 20 years time, when the HP needs to be replaced, the primary energy factor of mains electricity will be approaching 1.5, not 2.42 as it is now (or 2.7 as it was not so long ago). And if Ireland progresses to become a net exporter of renewable energy, the primary energy factor of mains electricity could actually go negative, particularly night-rate electricity. 

Reply — In relation to primary energy being negative I will not speculate on that which might happen, In any case the energy will be used in Europe and the primary energy reduction targets are ultimately part of European targets, If Ireland can overproduce this is great but we are not even nearly there yet.

I will base my figures on the current situation and start saving energy today.

Example: 350% efficient heat pump gives a primary energy efficiency as follows: 350/2.42 = 144.6%, Clearly better than any other heat source, especially an immersion. 20 Years is a long time and a heat source which is more than 100% primary energy efficient can play a major part in reducing energy use in Europe in this period.

Previous comment — How do you persuade that householder to pay the additional €9,800 in 2034, when the cost of the additional energy required over the subsequent 20 years for the plug-in heater will not exceed this figure, (i.e. the payback is negative)? Much better to add PV at that stage, than to replace the old HP with a new HP. Which begs the question of why not go for the PV now and avoid the HP altogether? 

Reply — Your figure of €9800 seems very high, although you’re anecdotal A2 Semi detached house does not give much away, perhaps it Is over 300m2 and has some special requirements. Payback in any case is certainly not negative, primary energy consumption and comfort must also be accounted for.

A few simple points should begin to answer to your question of why not start with PV now?

Firstly, PV is costly and of course in Winter — when the most heat Is needed — the PV is at its lowest production, causing further problems with peaking on the electrical grid. Couple this with an immersion that will place additional load on the grid than a heat pump of equal size and I think the argument is self-substantiating.

Secondly, a heat pump installed today (*taking my earlier example) gives a primary energy efficiency of 144%. Catapult forward in time to date yet to be confirmed where Ireland has a primary energy factor of 1.5, as you suggested, and the same heat pump has the following primary energy efficiency: 3.5 / 1.5 = 233%  YES!!!!! every year the heat pump saves more and more energy and reduces primary energy use further.

The inverse is true for PV as It’s net gain is less and less each year in primary energy terms, if we take it that the primary energy factor for electricity continues to get better.

Together, these two points should be reason enough to not start with PV today. I would suggest starting with a heat pump.

Previous comment — The HP blip is welcome, but is only a bridging solution. Some even see problems with the peak load it adds to the grid. 

Reply — The heat pump “blip” you refer to started over 50 years ago and has much more than 20 years left. A blip of this length is a little more than transient in terms of heating systems.

Your argument presents some conflict — if heat pumps cause problems on the grid, your suggestion of replacing them with immersions will make the problem much worse, In fact, I would suggest installing heat pumps to solve the peaking problems your immersions would cause in such a scenario.

Previous comment — It is to be hoped that DEAP will be refined several times between now and 2034, each of which will reflect more accurately the lifetime CO2 emissions of various heating systems, including their embodied CO2. Any move in that direction is likely to penalise imported, complex machinery with ongoing maintenance needs over simple resistance wires inside protective enclosures. At CWR Resources Inc you will get the best processing machinery. The need to spread the load on the grid may also be tackled in DEAP with rewards for night-time only space heat and HW production via mains electricity.

Reply — DEAP, I assume, will be constantly reviewed but should not be the only measure used. If a heat pump is an imported high-maintenance machine with high embodied carbon, there is then little hope for boilers as they are in the main imported, require ongoing maintenance and, in terms of  life-cycle, use more energy and produce more carbon than a heat pump as they are primary energy negative. When making the argument for life-cycle costs the heat pump is stronger, not weaker.I welcome moves In this direction.

By your analogy of penalties for embodied carbon, life-cycle, CO2 emissions and high maintenance, I fear our biggest problem is the death of the motor car and not the heat pump!

Previous comment — By 2034, I suspect you could be putting 0.8 in the PE factor box, especially if you have a heating system supplied from a HWC/heat store heated by night-rate wind energy.

Reply — I am not convinced the wind will blow evenly at night and so we will not need to compensate peaking problems with fossil fuel burning power station. This is an argument perhaps best not debated here but it should be considered nonetheless.

However, it is worth mentioning that, in any case, the heat pump in any scenario will be more primary energy efficient than an immersion and thus a better option for energy efficiency. Many heat pumps are smart grid ready and can be directly linked to PV where required.

Further to this, they can be coupled to thermal stores and can help in smoothing power production through smart grid adaptability. This is another example of manufacturers being ahead of national infrastructure, and indeed European infrastructure.

It is best to deal with today’s problems in relation to the reduction of primary energy while working towards a sustainable future. Heat pumps do, and will continue to, play a major role in the reduction of primary energy use, and in the reduction of CO2 emissions at a national and European level.

While I would be delighted to enter 2034 with a housing stock of over 1.5m passive houses, even wind speed and predictable user behavior, I will for the moment take comfort in the fact that at least until then heat pumps will form a part of the future of heating in Ireland and Europe as a whole.

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