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IET Guide to Implementing Electrified Heat in Domestic Properties launch webinar

If you missed the webinar, you can still view it on-demand.

Your questions answered

Will the service cable for domestic premises need uprating as EV is also in the mix? Also, where will the extra generation be provided from as it would require more CCGT output?

Service cables in existing properties may need upgrading, but each case is different, so it is recommended that this is assessed carefully by an experienced professional.

Maximum demand is a topic that is being discussed within the IET. It will be affected by new loads such as EV and heat pumps etc. However, time of use controls also should be considered to mitigate peak demands.

Grid level solutions to decarboinised energy will be required, but this guide is focused more on end-use and here energy efficiency and controls will reduce the impact of new technologies.

How do these systems function in old poorly insulated buildings?

A heat pump will perform better in a building that is insulated to keep heat inside, this applies to all buildings regardless of the system used.

Surely it is totally unrealistic to expect to replace our massive gas pipework network with Electrified Heating, especially in large multistorey buildings?

I suggest you look at the work of the National Grid and the Future Energy Report they produce. While I am not an expert on this transition with regard to the demand side, this document gives a lot of information on what is and could be done.

Will the presentation be available to view later?

Yes, the presentation will be available on demand.

I have heard that ground source heat pumps will, over time, exhaust the heat source in the ground especially if a number of neighbours are trying to extract heat from a relatively small volume of ground. I have also heard that the ground needs to be rested from time to time. Could you say something on this, please?

When applying ground source heat pumps, consideration needs to be taken to ensure that the ground is not stressed too much, spacing of boreholes and ground arrays, surveys of the conductivity of the soil etc.

Future of the Power Network - with the increase of Heat Pumps on the LV networks, how do we cope with the Harmonic pollution?

Section 6.1.6 describes the need to ensure equipment does not cause a detrimental effect on the grid, e.g. from harmonics, and lists the BS EN / ISO 61000 standards for heat pumps to demonstrate this risk is minimised.

Is the current market of heat pumps suitable, efficient and effective for all homes (including affordable homes)? Also, at the moment electric heating is more costly than gas heating (installation and running costs), would that change in the near future?

There is some discussion underway to tip the balance between the costs of electricity and gas. At the moment any levies are attached to electricity which is a resource that is generally getting 'cleaner' - this should not be the case. There is a heat pump solution that will serve most homes, small to large 'cascade' systems that work together to offer bigger loads.

My experience of nighttime storage heaters as a child growing up in the 70s wasn't great. Our bedrooms were freezing cold in the mornings when we got up and the stored heat was also all but spent by the time we got home in the afternoon. Of course, the house was lovely and warm during the day when no one was there but evenings were spent wrapped in blankets. It was also really expensive even on an Economy 7 tariff. How will it be different this time around?

Modern storage heaters are very different to the ones of 30 to 40 years ago. They are better insulated and a more compact design. They can also have supplementary heating in addition to storage heating.

Additionally, the controls are much more sophisticated. They are highly suited to demand-side management and hence offer a flexible source of demand which is likely to be valued by the grid.

The concept of Economy 7 with night time storage is more likely to be replaced with storage or charging that can occur any time of the day or night, with modern storage heaters being far closer to batteries and EVs from a grid perspective, and closer to traditional 'heat on demand' systems for consumers.

Do heat pumps with inverter technology require a type F RCD?

It is possible that a type F RCD may be required for a heat pump radial circuit. The heat pump manufacturer's literature should always be consulted when selecting appropriate circuit protection for the equipment.

Is there a reason why heat pumps are preferred at the moment and would they become more efficient (at low temperatures)?

Heat pumps are a favoured option as they are readily available today, can be widely applied and work well in a wide temperature range that covers the UK climate.

I have a large Victorian house - 13" solid walls (decorative brickwork outside, decorative plasterwork inside) and a 50kW gas boiler. Is my house going to become uninhabitable with no gas? Will the guide give me an answer?

The guide will assist you in determining the heat demand of the house and the sizing of the heat pump to meet your requirements.

If the heat demand is too great for a domestic (single-phase) heat pump then it will assist you to investigate insulation options to reduce heat demand. However, nearly half the UK's buildings were constructed before WW2 and have very poor levels of insulation and limited scope to improve insulation to the levels needed to be suitable for heat pumps.

This can be further complicated by planning restrictions. An alternative is to install a larger 3 phase heat pump but this will incur additional and potential significant connection charges from your local distribution company.

What type of system could work better for economy 7 property?

It depends. A modern well-insulated property with low heat demand may be well suited for storage heating.

The capital cost will be lower but the running costs will be higher as the efficiency is ~100% compared to ~270% for a heat pump.

Can we see a comparison in terms of kWh required to heat a home?

An average pre-WW2 building will have an annual space and water heat demand of ~15MWh compared to a post-2000 building heat demand of ~7MWh.

One big issue with our housing stock is improving thermal performance and balancing those costs against heating solutions. How well does the guide cover these aspects?

The guide has a complete section on building fabric and comfort considerations.

Are there options to utilise log burners to provide hot water and heat to radiators? There are approx 2.5million homes in the country with these installed.

No. The guide focuses on electrified heat.

Is the guide available as an ebook?

Yes, the Guide to Implementing Electrified Heat in Domestic Properties does come in an ebook version. 

With respect to section 6 of the guide: What planning and potential impact on DNOs has been considered by the guide and the DNOs?

Section 6.2 describes the process for engaging with DNOs and applying for upgrades or new supplies where these are required.

As explained within Section 6, DNOs are planning for infrastructure enhancements to cope with increasing demand and their application processes should identify where new supplies are required as well as setting requirements for installations such as power quality.

Does anyone have experience of major infrastructure being required following an application to a DNO?

The guide mainly focuses on the requirements of individual dwellings.

With respect to large scale developments, yes, I have experience of that, but it is not quite within the scope of this document.

Does the guide include the ENA requirements for applying to the DNOs for new heat pump installations?

Yes, it does include references and snapshots of the ENA application process for low carbon technologies including EV and heat pumps.

I am at present carrying out complete renovation including underfloor heating, new boiler etc. The cost for electrified heating is very high at the moment and the skillset for design and installation is limited. The question is does the guide provide me with guidance as to what I can do now which will allow me to change over to electrified heating when technology is developed and more commercialised?

Yes, the guide will be helpful.

Underfloor heating is very important and so it is good that you are installing such a system.

High levels of insulation are also important and the guide will help you determine the benefits which can be evaluated.

Water storage is very important and depending on the size of the house you may wish to go for the largish facility, >200 litres and possibly heated with a separate heat pump.

You'll also need to ensure that you have given consideration to the location of the heat pump which is suitable for retrofitting and in compliance with building controls.

Is there any rule of thumb with respect to the expected load increase for a property? I realise that this will be varied depending on the age of construction.

The guide provides advice on how the reader should go about evaluating the scenario at hand as there is no one size fits all solution. It encourages tailor-made solutions.

At this moment we are currently supplying our demand in the UK with CCGT of almost 45%. Aren't we just going to increase the amount of gas generation at the source?

Projections by the Committee on Climate Change indicate that the UK will have a very different generation base in the future.

With significantly higher levels of renewables (wind and solar) supplemented by CCGTs operating on hydrogen and nuclear.

Natural gas is used to produce hydrogen with the CO2 captured and sequestered for safe storage.

Do you think it's counterproductive to be retrofitting and improving EPC ratings of older properties, whilst most new builds are not being built to the best efficiency standards and without any low-carbon technology installed? Should new builds be pushed further?

With circa 28 million buildings in the UK of which nearly half were built before WW2, the focus must be on improving the insulation levels of existing and older buildings.

These typically have a heat demand 2 to 3 times that of new builds and hence will make a much greater contribution to reducing UK heat demand than new builds, so it is not counterproductive but I do agree that new builds should be built to the best efficiency standards.

Where does the panel see the electrified heat install market heading in the future? Do you see big players such as Octopus energy dominating the market, or a continuation of SMEs/independent installers once upskilled?

It will be interesting to see where this goes over time, the introduction of specific tariffs in support of heat pumps, for example.

Heat as a Service is also another area that we may see - this has only been applied in limited applications so far.

Would it be prudent to write a non-technical handbook to assist homeowners in making an informed choice?

Interesting thought - thank you.

For a domestic homeowner to transition from a conventional boiler to an electrified heating solution, what is the estimated cost involved for a 4 bedroom house?

Typical figures assumed are ~£10k but this can vary significantly.

Do you have detailed Embodied Carbon data/projections to implement across the country?

Mitsubishi Electric response: Speaking for ourselves, we are doing a lot of work to publish the embodied carbon data of our systems. These are being released regularly in line with the CIBSE TM65 Methodology. Keep an eye on our Digital Document Library for releases.

GDHV response: We too are working on supplying similar information on our products so that specifiers and customers can see the data and include it in their decision process.

Have you produced a guide by use case that clearly sets out the pros and cons and business case in the various scenarios in which electrified heating would be used?

The guide reviews all options.

The business case section focuses on the most complex scenario of a heat pump. However, this is still applicable for other methods.

The guide encourages the reader to calculate their own business case and proposes a model to follow.

So all older houses such as terraced houses will not be adequately heated and for a greater cost? Has the average consumer been considered during this process? We are going to increase fuel poverty with this policy! Thoughts?

The most important aspect is to insulate first and reduce demands to a minimum.

I believe the local DNOs will tell a different story when requesting significantly larger supplies, there is just not the local generation in place to assist in the support of this demand for space heating and EV charging.

See answers to Q2, Q19, Q20, Q21, Q24, Q36

When cold, people touch heaters to get reassurance. New heaters don't feel hot - how do we change the public mindset especially the elderly, even when the room can be 22C and above?

Education of users of systems such as Heat Pumps will be needed, so they understand how they operate and what to expect.

As a manufacturer, we have created videos and mobile exhibitions to explain this to consumers.

Is there still a place for storage heaters as a heat source, given the additional controls they are now available with, to meet Lot 21?

Yes, absolutely.

In fact, much as they did in the nuclear era, they look set to play a significant role in the electrification of heat in buildings. Most prevalently in supporting the grid through flexible demand, and offering a solution for hard-to-treat homes.

What is the estimated extra capacity required for generation? Do we think we can supply all the heating for homes and all the energy for electric cars with our current supply? Is this realistic? (It is not practical either, but that's another story).

National Grid's Future Energy Scenarios project increases of 59-94% in peak electricity demand by 2050 and propose generation options to meet this demand.

It is not expected that we shall supply the needs of electrified heating and electrified transport with our current generation mix.

National Grid is planning for increases in both peak loads and total consumption of electricity.

Can you please also discuss the noise issue related to the outdoor heat pump installation? Are there any problems associated with noise penetration into the dwelling and disturbance to neighbours?

Modern heat pumps are very quiet, it is a common question we get and when you stand next to one that is working you realise quickly that they are very quiet in operation.

Permitted Development is also the place to look for any rules on their placement

(CS) On a practical level, I have run an ASHP for my hot water for over 5 years. I live in a cul-de-sac of modest-sized detached properties. You cannot hear the ASHP when it is running beyond my short driveway and we cannot hear it in the house. The neighbours do not realise it is running.

As policy is a key driver in the adoption of new technologies, do you think the government has the right policies in place to drive the adoption of electrified heating?

The Government has some appropriate policies planned or in place, including tightening carbon requirements in Building Regulations (although there is some variation among the UK nations).

However, current and planned policies are likely to be insufficient to meet the Government's own targets for electrified heating.

For instance, the UK Government has a target of 600,000 heat pumps per year installed by 2028 but the Boiler Upgrade Scheme is expected to support just 45,000 installations a year and tightening building regulations might be expected to stimulate only around 100,000 installations per year.

Does the guide provide advice on design and installation of ground source heat pumps? Many designers and builders are very reluctant.

The guide provides a page on key aspects of ground source heat pumps, including advantages and disadvantages.

Much of the guide's advice on design would be applicable to air source and ground source heat pumps. However, for ground source-specific design and specification, it is also worth considering good practice published by CIBSE and GSHPA, as well as the requirements and assurance provided by MCS.

One of the main issues with heat pumps installed to serve existing houses and particularly with newer high-density houses is the noise issue from the outdoor units. This is already causing significant issues where heat pumps have been retrofitted.

Noise issues has not been my personal experience - see the answer to S Karimjee's question.

It seems that the exhaust from heat pumps is cold dry air. What's your advice for positioning to mitigate the effect of this, and is this cold dry air source usable in some other way than simply exhaust?

Our installation instructions detail how and where the outdoor unit can be placed.

Commercial heat pumps are able to absorb heat in areas it is not required (creating cooling) and move this heat to where it is required, space heating, water heating or overdoor heaters in retail for example.

It seems that the cost of upgrading the insulation of a typical 1930's house is likely to be more than the cost of a heat pump. What is the trade-off between insulation and heat source costs?

The cost is likely to be comparable (on average).

However, regardless of the heating solution the UK should be improving the insulation levels of its buildings.

Not only does it reduce heating costs but it also contributes significantly to comfort and public health.

Cameron pointed out that an air source heat pumps can produce 3 times higher output compare to normal heating solutions, Is that only for hot water or including space heating?

The description included space and water heating, 1 kw of electrical energy typically generates around 3 kw of heat.

I works as a consulting engineer arranging new utility connections for housing developments. Currently in the Northwest if you opt for gas heating the electricity DNO will only allow a diversified load of 1.1kVA per dwelling when sizing the distribution mains. Opting for electric heating and car battery chargers that will be used at night when the electrical demand per dwelling will require significant pre-emptive upgrade of the electrical infrastructure.

Yes agreed.

Do external ground mounted heat pumps require any special consideration when supplied from a TNCS electric supply.

Installations of external units should follow the requirements of BS7671.

Appropriate earthing connections back to the supply and RCD protection are necessary. The manufacturers guidance should always be followed too.

However any special considerations should be no more complicated than traditional AC split units.

Does the guide give guidance on any de-rating to meet peakheat requirements on vs. cold days?

Yes. There is a section which illustrates how heat demand can be calculated.

I'm surprised and disappointed that storage heaters are regarded to poorly by the public. Shaun mentioned modern high heat retention versions. I've just installed one and it's very impressive with a very advanced control system. This strikes me as an excellent way forward being relatively cheap and controllable.

Yes agreed. For well insulated buildings with low heat demand they could be the best solution.

Is there much noise associated with heat pumps especially air source?

See answer 38.

Big hurdle for changing to diffrent heat system is cost! Goverment needs to help towards meeting the initial cost! Any thoughts on this?

This is an ongoing debate, the Renewable Heat Incentive was designed to assist in this but I agree there may need to be other incentives needed to get the mass market moving but then could be tapered away as it becomes the normal situation.

What analysis have you done on potentially competing decarbonising solutions, e.g. hydrogen fuel cells, against heat pumps, i.e. not necessarily electrical methods?

The guide focuses on electrified heat and not other sources of low carbon heat.

Why are there no women on your panel?

A good point and is noted for future committees.

Surely the best option in the short term is to improve the glazing and insulation in existing buildings. This will reduce the carbon used and lay the way for conversion to electric heating.

Agreed, this should always be the first step.

With the current energy prices it seems sensible to have a domestic battery system installed with a heat pump, even without solar, to take advantage of lower nighttime energy costs. Will there be a push from the industry and government policy for the approach?

At present, the economics are "challenging" but this is likely to change with reductions in battery costs. Of course, the battery on wheels outside your front door provides an option and this is currently being explored.

Re Martins water to water type heat pump, has anyone given any thought to harvesting heat from sewage, which probably arises at a higher temperature than other water sources?

We have had discussions with water companies on exactly those types of systems.

What are the cost differences, payback period and increased internal, and external space required to install a heatpump?

These topics are covered in the Guide in the business case section.

It is no secret that heat pumps cost more than a gas boiler. However, the economics are changing with the rise in gas prices which are growing faster than the corresponding electricity prices which indeed favours heat pumps.

I would suggest taking a look at the business case section in the guide for full details.

What happens when a property is the last one in the street using gas heating. Are there protections to prevent the gas supply to someone who may not be able to afford the cost of conversion to electric heating from being cut off?

This is an issue to take up with the utility providers I am afraid.

Converting an existing wet heating system to run with a heat pump will require replacement of pipework as well as radiators. Experience has shown that 10mm pipework installed over the last 30 years cannot transfer water at 55Deg C and provide the level of heating required.


Might not be the correct forum to ask but if using electricity to existing properties isn't efficient (poorly insulated), and we don't want to lose a national asset (gas network), is a sustainable option to look at electric heating for all future properties with a view to replacing natural gas with hydrogen for existing properties?

Regardless of the heating solution, the UK should be improving the insulation levels of its buildings. Not only does it reduce heating costs but it also contributes significantly to comfort and public health. However, there may be many buildings and inparticular commercial buildings which may be better suited to a hydrogen solution using the natural gas grid. This is the subject of considerable investigation by the industry and government.

How do we deal with the harmonic emissions from heat pumps?

See answer to Q7

With electric space and water heating, electric showers and electric vehicle charging points, will new build houses need more than the standard single phase 100A electricity supplies in future or can energy efficiency and smart control of appliances keep it below 100A?

The main concern is the distribution feeder.

Typically the local distribution network operator will adjust the rating when planning to take account of diversity amongst building connections (sometimes referred to as peak coincident factor).

So even though the building may have a 100A connection (circa 20kVA) the diversified rating will only be 1 -2 kVA.

The additional electric load is likely to require an increase in the diversified rating which will require the network to be reinforced. However, the 100A connection itself will probably be sufficient.

Older properties rely on drafts to maintain the fabric of the building in good condition. If the conversion to electrified heating relies on a highly insulated home, has the effect of eliminating drafts been considered for older properties?

Well insulated buildings require ventilation for reasons of comfort and health and this should be considered. Typically these mechanical ventilation systems with heat exchanges to reduce heat losses.