Mr. Seamus Hoyne:

That is another great question. This also relates to the question about windows. There has been huge technical development around heat pumps in recent years. Research in TUS and the team that works with me here have seen various reasons for what I might call the under-performance of a heat pump. First is that they might be over-sized. That returns to a point made by Deputy Bruton earlier. There was a tendency for over-specification for heat pumps in some cases. Where a 6.5KW heat pump was needed one of 8.5KW was installed. In some cases that is a safety measure put in by the engineer or it could be a cultural thing where if we put in an oil or gas boiler the price difference between a 20KW or a 25KW boiler is minimal so we just put in the 25KW boiler, for example. However, over-specification for a heat pump has implications for its operation. Without getting too technical there is a cycling of that heat pump and its overall efficiency drops. Our longitudinal study found that in some cases the heat pump was oversized and its heat curve was inappropriate for the building.

The second issue is on commissioning. Typically in a retrofit we are moving from a solid fuel heating system or an oil or gas system to a heat pump. We hear people say that you just leave the heat pump on all the time versus the oil boiler coming on for two hours in the morning or four hours in the afternoon. In fact, typically a heat pump is controlled by a heat curve that looks at temperature. The heat pump is available to be on the majority of the time but the controls are such that the heat pump will just provide enough heat into the building to keep it at a particular temperature. One challenge is communicating the operation of the heat pump to the building owner in the retrofit because it is a new way of living in your home and heating your building. Sometimes well fall down on that. There is an onus on the installers and contractors who are delivering the work to make sure they understand. Our research found evidence where the homeowner was blissfully unaware that the heat pump was underperforming but they were perfectly happy because they were living in a very comfortable retrofitted home compared with where they were previously. We were able to do tweaks in the back end for those homeowners that improved the performance of their heat pump but that did not effect their overall comfort levels. There is still a lot of new product technology emerging onto the market. We need to make sure, and manufacturers are very keen on this, that if I am installing a particular heat pump type that I am trained on that particular technology. They have their own training centres and programmes to make sure their heat pumps are installed correctly and commissioned appropriately because if not their warranties can be voided.

Generally, I would say that the operational performance of heat pumps is very good. Our study found that they were operating with coefficient of performance, COP, of over 3.4 which for air-source heat pumps is very good. That means that for every one unit of electricity put in they we get 3.4 units of heat into the building.

My colleagues may wish to respond on the building energy rating, BER, system in traditional buildings. The system and the methodology has changed in recent years.

The SEAI and the working group that oversee it have brought in many changes. We see very different profiles of buildings now. This is because we are reducing heat loss through the fabric and the energy consumption from lighting and from domestic hot water, which is now much more important. The BER tool, or the dwelling energy assessment procedure, DEAP, has been modified to take that into account. Can it be improved? Absolutely. It is important to understand that the BER tool is what we call an asset tool, which means it is based on an assessment of the assets of the building, on the specification of the heating system and on the fabric of the building, such as the windows, the walls and the distribution system.

As Dr. Engel Purcell mentioned, in some cases we may have to use default values that do not represent the reality on the ground. This is because of the standards that are required by the DEAP tool. We therefore get what are called energy performance gaps, between what our dwelling energy assessment procedure tool tells us and the actual energy performance. Overall, a working group is continuously looking at upgrading the BER and the DEAP tool.

My final point is on windows. Without getting too technical, it important to think of the window as being made up of a couple of components. The first of those is the glazing, the second is the frame and the third is how the window is connected to the building. The glazing is therefore only one part of the energy performance of the overall window. There have been huge advancements in the overall performance of the window components and the entire window frame and glazing. Some of our companies in Ireland are at the forefront of that. We look at this on a case-by-case basis. A building that was built before 2006 might have poorly installed frames and windows that might be introducing thermal bridging, infiltration or poor air tightness into the building. It makes a lot of sense to consider an upgrade of the windows in those situations. When we look at traditional buildings, it is much more complex to make those decisions.

We talk about double glazing versus triple glazing. In many cases, there are now products on the market where a double-glazing product is as effective, as efficient and has a U-value that is comparable to triple glazing solutions. Therefore, there are good technical products out there. If installed, they can give multiple benefits not just for the fabric but also for the overall efficiency. They also start to address air tightness issues and thermal bridging issues around the openings in buildings.