Embracing electric heating
Make sure you’re ready to make the most of the rapid revolution in home heating
While the results and commitment from the recent COP27 were disappointing, it’s reassuring that the industry and public at large are already making significant steps towards decarbonisation.
For the electrical contractor and electrical supply chain in general, these steps present huge opportunities as most aspects of the path to decarbonisation involve the electrification of nearly everything.
The decarbonisation of transport is well under way through the growth and exponential uptake of electric vehicle (EV) sales, with pure electric and plug-in hybrids currently accounting for 20.8% of total car sales. However, the issue remains on how to decarbonise our built environment, particularly the aspect of heating.
Space heating and cooling account for 17% of carbon emissions in the UK, with 13-14% attributed to domestic homes.
Most of our building stock is reliant on fossil fuel heating via burning mains gas or heating oil, both major emitters of carbon dioxide (CO2) and other climate-breakdown related emissions. Therefore, the only viable way the UK can decarbonise our heating systems is through the electrification of heat.
What about hydrogen?
It’s important to bear in mind that there exists an abundance of misinformation regarding how hydrogen will be the saviour to our heating problem.
It’s equally important to understand that the major bodies behind the hydrogen lobby are incumbent oil and gas companies and those with vested interests in the existing supply chains and infrastructure.
While ‘green’ hydrogen can be produced through electrolysis of water using renewably generated electricity, it would be more efficient to use the electricity directly. Using renewable electricity to create, store, transport and use hydrogen results in heating efficiencies of around 46%. Direct use of electricity, including loss of efficiencies in transmission and distribution, is around 90%.
Secondly, the bulk of intended hydrogen use would likely come from ‘blue’ hydrogen, created from natural gas being put through a steam reformation process, with the CO2 by-product captured and stored. This is a mechanism known as carbon capture and storage (CCS).
CCS is not fully developed or proven as a technology for mass deployment. Pipe embrittlement, both supply side and behind the meter, and a lower energy density requiring two and a half times the volume of natural gas are further issues often not discussed regarding hydrogen. The direct use of electricity for heat is therefore the best solution.
Let’s start with heat pumps
These are widely known to be a great option and are commonly available as air source heat pumps (ASHP) or ground source heat pumps (GSHP), with the latter only viable where there is a suitably sized large garden, to prevent ground freezing. Water source heat pumps are also available for extracting heat from rivers and lakes.
These pumps operate like a refrigerator in reverse, ‘upscaling’ the latent heat in air (ASHP) or underground (GSHP). Since the latent heat is upscaled, incredible efficiencies are realised, with typical Seasonal Coefficient of Performance (SCOP) factors being between three and four. This means that for every 1 kW of electricity used, 3-4 kW of heat will be produced.
Most heat pumps being installed in the UK are air-to-water/ground-to-water, which as the name suggests, uses a wet heating distribution system – the type most central heating systems use.
Unfortunately, due to heat pumps operating at a lower temperature, which equates to higher SCOP values, the heating emitters and sometimes the distribution pipes may need to be upsized to allow the same amount of heat to be delivered. This can result in additional costs and upheaval to the building owner/tenant.
As an aside, it’s worth noting that if heating engineers had designed and installed condensing boilers to operate efficiently and correctly, i.e. 60°C or lower, emitters would likely to have been upsized to a usable size for heat pumps, thereby removing this additional cost and negative ‘narrative’ that often accompanies the arguments against heat pumps. Wet distribution heat pumps are a true mechanical and electrical installation, requiring the skillset of an electrician and a traditional heating engineer, both of whom should have the relevant upskilling training.
Commonly installed throughout continental Europe, air-to-air heat pumps are also a valid option and are well suited for installation solely by an electrical contractor. Split-systems resemble common air conditioning units and are similar, but with the option of providing both heating and cooling.
Individual rooms can have their own heat pump or the property can be satisfied via a common ducting system. While the air-handling unit may be unsightly to some, they’re quicker and cheaper to deploy.
The only slight sticking point for an electrical contractor? Air-to-air heat pumps commonly use fluorinated gas, so you’d need to be suitably trained.
What are the alternatives?
There are also a number of other viable low-carbon electric technologies, particularly for properties with low-thermal demand such as new builds or buildings that have undergone extensive renovations to Passivhaus standard or similar.
These options include infrared (IR) and smart electric thermal storage, both of which have high efficiency and can be assumed to have an efficiency ratio of 1:1, i.e. 1kW of electricity in equals 1kW of heat output, albeit with minor losses.
Additionally, these systems require no to low maintenance once installed, as opposed to heat pumps which have more components and moving parts, thereby requiring regular servicing.
Due to the extended operation time of an electrical heater, a dedicated heating circuit should be provided. BS 7671 Appendix 15 should also be considered with regards the following statement relating to ring final circuits:
The load current in any part of the circuit should be unlikely to exceed for long periods the current-carrying capacity of the cable (Regulation 433.1.204 refers). This can generally be achieved by: (ii) not supplying immersion heaters, comprehensive electric space heating or loads of a similar profile from the ring circuit.
The advantage of infrared
IR heaters can be rapidly deployed and are relatively unobtrusive, with a number of manufacturers offering slim IR panels for walls and ceilings and even disguised as picture frames.
The technology works by heating objects in a room through emission of IR radiation which is absorbed and re-emitted. As a result, properties are less affected by loss of heat through draughts, and doors opening.
While individual IR panels can be plugged in via a BS 1363 plug and socket, it’s advisable for professional installation and connection via a fused spur on a dedicated circuit.
How about smart electric storage heaters?
Used in the UK for decades, today’s storage heaters are greatly improved and efficient, particularly since the adoption of Lot 20 compliance, which enforced strict efficiency requirements.
Smart electrical storage heaters can be compared to Economy 7 style heaters of the late 20th century, but with better thermal delivery and user comfort.
Electrical thermal storage of all forms, e.g. immersion heaters, is generally favoured by Distribution Network Operators (DNOs) as they offer low-cost grid flexibility. Through time-of-use (ToU) tariffs, users can be encouraged to take energy from the grid during times of excess generation, e.g. late at night or during high amounts of wind-power generation, and reducing usage during ‘peak-times’ such as 4-7pm. The result is a smoother network energy demand curve as well as lower costs to customers.
Smart electric thermal storage could be configured to operate according to DNO signals, like smart EV charge point regulation requirements, or work with load control to ensure that a user’s maximum electrical demand does not exceed the fused rating. Alternatively, they could operate on a separate circuit controlled by the smart meter in a similar fashion to ‘traditional’ night storage heaters, although not all smart meters provide this functionality.
Some 80% of the buildings that will be with us in 2050 already exist and most of these will need to be retrofitted to increase their energy efficiency.
Regardless of the type of heating being deployed, reducing the thermal loss of a building should always be the first port of call. While often outside the scope and remit of an electrical contractor, this will offer the best energy and emission reductions for the client and then allow for a correct heating design to be carried out.
Holistic retrofitting requires a coordinated approach, so if a heating source is designed and installed prior to reducing the heat loss, the heating system will be oversized and inefficient. For holistic retrofits the PAS 2035 retrofit standard found at knowledge.bsigroup.com should be followed. While currently a paid-for publication, it is due to be made freely available soon.
Heat loss calculations
In order to ensure that the heat source, i.e. heat pump, and the heating emitters, i.e. radiator, IR panel or smart thermal storage, are correctly sized, it is imperative that the heat loss is understood at a room by room level.
This entails analysis of the building structure, including the make up of the walls, type and size of windows and doors and dimensions of the rooms. While this may sound onerous, this can be easily worked out through freely available tools, such as the MCS heat pump calculator which is available at www.mcscertified.com and is compliant with BS EN 12831. Alternatively, this can be undertaken by specialists.
Smart heating controls
Smart controls are another growing opportunity for today’s electrical contractor. Customers have already invited the notion of a ‘smart home’ into their dwellings through the adoption of plug-and-play smart speakers, video doorbells and similar.
The smart ecosystem includes a whole raft of devices that offer solid energy savings, particularly with heating and lighting. Combinations of smart thermostats along with smart thermostatic radiator valves (TRVs) allow users increased comfort customisation as well as running a more efficient building.
Mobile phone apps can be used to adjust individual room temperatures or set heating profiles, as well as sensing when a registered user has left the property and automatically reduce the temperature, a process known as ‘geofencing’.
When the user returns within a certain distance of the property, the heating gradually increases so the house is at the right temperature when required, without wasting undue heat due to being unoccupied.
All this means that, as our buildings become smarter, our devices will need to work better together and energy flexibility will be key to maximising our electrical energy systems.
Opportunities lie with the role of the technology ‘integrator’ and being the trusted individual for your client and the expert who can join the dots and make these systems work.
Luke Osborne Energy and Emerging Technologies Solutions Advisor
The SELECT verdict
It’s clear a revolution in heating is coming, so it’s vital that we maximise the available workforce to keep pace with the technology outlined on these pages.
With electrification at the heart of nearly everything that lies ahead, electrical contractors have an excellent opportunity to upskill and grab new chances with both hands.
It’s also a real opportunity to break down the traditional barriers which have portrayed heating as something that’s only ever done by plumbers.
As a sector, we have to embrace a skills crossover, with a greater understanding between the different disciplines, and electricians playing a more active and holistic role in heating.
Above all, we need to make the heating and electrical sectors one and the same – with electricians leading the way and acting as integrators, not just installers, of this exciting new technology.