In this case study Kev Matthews tells us how he’s navigated the Wiltshire Planning system on his journey to install an Air Source Heat Pump in his Calne home…
…With the Boiler Upgrade Scheme from the UK government contributing £7500 (England and Wales) towards the cost of installation, it’s never been a been a better time to consider this alternative to Gas Central Heating and Hotwater. Our journey towards Air Source Heat Pumps is under way and I felt it would be useful to share it because we’ve needed to apply for Planning Permission and while Planning Rules are changing*, inevitably some installations will still need planning and this can feel daunting to a home owner – certainly it’s how I’ve felt along the planning process.
*Under the latest NPPF changes permitted development now allows more than one heat pump on a property. Nonetheless you may still need to apply for Planning Permission for listed buildings, or in the conservation area, or your heat pump location fails MCS noise requirements at your neighbours nearest habitable window.
The Property
It’s a 2012 standard construction 4 bed detached house on a corner plot, it is an “L” shape, but we have filled in the missing bit with a single storey extension to make it a square. As part of the single storey extension (2019) we added Air Conditioning to the living room and two of the bedrooms though a Mitsubishi Air Source Heat Pump – it has the ability to Heat as well as Cool, though the primary use is Cooling in the summer months. The House is otherwise heated with a Potterton gas system boiler which was installed when the house was built and 180L Water Tank in an upstairs airing cupboard.
In August 2024 we added ~7.9kW of Solar PV followed by a 13.5kWh Battery and Inverter in November – Our plan was to look at replacing the boiler in spring 2025 once we knew where we were in terms of Solar Generation and Battery use, but the annual boiler inspection in September threw the curve-ball of “CO leak and badly corroded gas pipe” which resulted in it being instantly condemned as “Immediately Dangerous” and a nice quote for £3500 for a new “efficient” Gas Boiler. This really pushed us forward with a decision to move towards a Heat Pump.
Why a Heat Pump?
The energy crisis of 2023 allowed us to take stock of how we power and heat our home, with energy getting ever more expensive, it was time for us to look at changes, especially as my household works from home. This lead us toward Solar and Battery Technology, smart tariffs that integrate with Smart Meters allow cheaper slots when the grid is greenest, allowing us to store cheap electricity in the Battery or cheaper slots to generate hot water overnight.
The Bulk of energy use in a house hold comes from Heating and Generating Hot Water, so the more efficient we can make this the better, with the most efficient Gas Boilers being ~92% efficient when you look at a heat pump which can be unto 400% efficient it starts to make sense that this should be the future. I’m sure there will be thoughts on Gas being cheaper than Electricity, this is true – however the efficiencies of Heatpumps and smart tariffs should allow this to balance out and be cost neutral or in some cases savings through Heat Pumps.
Since we also had a CO leak on our boiler as well as a corroded gas pipe, the other reason was to remove these harmful gasses from our house – Carbon Monoxide and Natural Gas are something that should not be inside a properly and the harsh reality for is is that we were very lucky to discover the leak when we did. Heat Pumps do not produce CO, nor can they leak explosive gas inside of the property.
There will of course be some debate on the future of Hydrogen to run boilers*, indeed some new boilers are “dual fuel” and promoted as Hydrogen Ready. I would encourage you at this point to listen to Greg Jackson – CEO of Octopus Energy talk on “Green” and “Blue” Hydrogen, but the bottom line for me is that it’s still putting a very potent gas inside the home and still involves the use of Power or extraction of Methane gas to create Hydrogen – you can listen to him talk on this here:
*Zero Chippenham agree – hydrogen is highly unlikely to be suitable for home heating systems as the molecules are too small – electrify everything!
Starting the Process
Who do you talk to for getting a heat pump, I’d been doing a lot of research in prep for our “spring project” and I’d settled on looking at Octopus Energy (our energy supplier) we also looked at them for our Solar install (but went with another vendor for this) and Vaillant. Both are market leaders in their own right for Heat Pumps, there’s no right or wrong here, just personal preferences and what works for you or your household and of course price point.
To qualify for the Boiler Upgrade Scheme, it needs to be an MCS certified installation, which is a Heat Only Heat Pump and no “hybrid” systems that contain a gas boiler. As part of this, you need to make sure your property has an up to date EPC (within the last 10 years, we did not) and your house will have a Heat Loss Survey from your installer to calculate the size of heat pump required along with assessment of your radiators to see if they need upgrading. Heat Pumps are generally “Low and Slow” compared to Gas Boilers, so you need bigger “emitters” or Radiators as we home owners call them! There is also a mindset shift for home owners when it comes to heating your home, so if you’re expecting to just fire up a heat pump when you get home in the evening and have a toasty warm house in an hour, just like your gas boiler- prepared to be disappointed! Doing it this way is also very inefficient too!
We managed to get an online quote from Octopus during Heat Pump week and then signed up for the survey and the surveyor came out a couple of weeks later and spent several hours taking many measurements, looking in the loft, measuring insulation and asking lots of questions. I also enquired with a Vaillant on their heat pumps and was directed to three local installers – one declined to quote at all and the other two came out to visit just after Octopus.
The local installers were here for less than 45 minutes each, one didn’t provide a quote following the visit and the other came in at an estimate of £6500 after the BUS Grant – ouch!
Octopus came in at around £1000 for a Cosy 6 (their own brand heat pump) after BUS and with extra discounts due to their Heat Pump week promotion (You can also get referral codes from another Octopus Heat Pump Customer to take another £100 off). This also included external trunking which I had to ask for – and I recommend that you do, because it looks better than lagged pipes on your outside wall, and most radiators being replaced for slightly larger ones – this price also included 2 out of schedule radiators that met the spec required, but I wanted replaced because they are rusting externally.
The main issue for us was that we needed to apply for planning permission, because we had an existing ASHP which counts as our one allowed under permitted development rule. This was an additional expense of £328 to factor into our costs, as well as a new EPC as ours is over 10 years old (but Octopus said they would cover the costs of the EPC as part of the install, so we’ll see that £65 back at some point).
Applying for Planning Permission
Octopus provide a guide for how to apply for planning permission via the national planning portal, the wording they use is very basic and this was probably my first error, in future I would also include something along the lines of – This installation has been designed by an MCS accredited installer.
I created my own scale drawings of the elevations and location of the heat pump to show where it resides. I used a location plan from my builders application for our extension and marked the plan up with the location of the heat pump. I also attached location photographs / street view pictures and the spec sheet of the Cosy 6 Heat Pump.
Plans have to be PDF format and scanned at A4 with a scale and scale marker – my mistake was submitting as a picture that I took, rather than a scan, so my application was rejected by the Validation Process and I had to scan the plans, which wasn’t a big deal, but delayed the application by a week, which was frustrating.
Once submitted it goes to consultation, The Public Protection Office are invited to comment, as well as the Town Council and your immediate neighbours, they have around 4 weeks to do this – as soon as the planning application went live I called my planning officer to explain our situation around lack of heating and to ask for advice, what I could do – they advised me on the process, what happens next, that it’s best to speak to my neighbours to gather support and basically to be patient and sit tight – not something I’m particularly great at!
The Public Protection office sent back an initial comment on my application which was as follows:
“No development shall commence on site until a Microgeneration Certification Scheme (MCS) accredited installer has demonstrated the Air Source Heat Pump (ASHP) installation will meet the requirements of the MCS Planning Standard; and the ASHP will produce a noise level of no more than 42dB LAeq (5mins) at the nearest bedroom/lounge window when operating; through source noise level data, distance attenuation and screening calculations. MCS compliance certification must be submitted to the LPA within 3 months of installation. Reason: Core policy 57, Ensuring high design and place shaping such that appropriate levels of amenity are achievable. If it is not going to be PD then we would look to implement tighter noise limits on the device as set out in our guidance document which I have attached but the applicants need to complete the MCS calculation first.”
My first thoughts on the comments and document from Public Protection was “please tell me what you want in plain English!” I am almost sure responses are geared towards professional design / planning people as opposed to home owners, and I know strict rules apply, but I feel there is work to be done here – so lets break this down!
Breaking the Planning Permission response down:
Permitted developments (PD) cannot exceed 42db of noise at the nearest bedroom or lounge window for more than 5 minutes.
However – if it’s not PD then – at least in Wiltshire – stricter limits of 35db apply (Wiltshire being a rural area and background noise is lower – as the given reason).*
*I have seen some applicants outside of Wiltshire successfully use the Government’s freely available LDEN noise maps to show that background traffic noise is greater than the heat pump noise in their location. Though in Chippenham only the town centre area is mapped – Matthew ZC
I had already attached the specs of the Cosy 6 and photographs showing location and distance to neighbours to the application but this wasn’t enough, so I had to put together calculations – something I would have done from the off if I knew what I know now!
Public Protection linked me to a complex set of documents and a calculator to complete the measurements – you can find the calculator here:
Calculations
As it turns out, it looks more complex than it is – but a few things you need to know:
DB of the ASHP – use the highest number you can find – eg Hot Water Cycle, the Cosy 6 has two numbers on its spec sheet 53.4 and 56.5 – I used 56 for calcs (.5 and below is round down anything .6 and above round up for noise)
“Q” Number – 2,4 or 8 – it’s a multiplier, basically 1 reflective surface (a wall or a floor) is Q2, 2 reflective surfaces (eg, wall and floor) is Q4 and 3 reflective surfaces (eg placing it in a corner) is a Q8 – a reflective surface is anything that is 1m or less away. 4 reflective surfaces is not permitted under MCS standards.
Barriers between the ASHP and neighbouring lounge/bedroom windows:
A barrier is classed as a solid wall or fence – NOT a hedge or row of conifers etc that you might typically find between your properly and your neighbours.
There are essentially 3 values: -10 (cannot see the Window), -5 (can see any part of the Window) and 0 (can fully see the Window) – this is from the point of measurement and 25cm in any direction from the point of measurement. This means that if you can’t see it at all it’s -10 which is great, but if you move and can see the part of it, then it drops to -5 and less great, and if you can fully see it then it’s 0 and not amazing at all – especially if it’s close!
Distance from the ASHP to the Bedroom / Lounge window – this gets fed into a calculation and gives a value – I used the values from Google Maps and rounded down to the closest meter.
You can play about with the numbers in the calculator – but as an idea, a 60db noise, 2 reflective surfaces, 8 meters away with no barrier will give you 43db which is over the allowance even for PD, where as 56db gives you 39db which is why if you’re looking at a supplier like Octopus, they will recommend a Cosy over a Daikin when it comes to your survey results.
I submitted a 14 page response back to Public Protection, detailing why I was removing the boiler and a lot of measurements to show all of the neighbours under consultation, this included distances using Google Maps to show each individual properly and the methodology on how I came to the decision on which measurements applied.
I also added a 3db gain to a separate set of measurements – this is significant because of the way that sound calculation works, 3db essentially doubles the noise, so this takes in to account cold weather operation, defrost cycles etc and gave me a bit of a margin incase of further objections. All of my calculations showed under the 35db limit required by Public Protection. For good measure, I also included a 10db calculation to the closest facing window and this was also still under limits.
+3db Calculation
Public Protection raised no objections following my detailed assessment (commenting that it was comprehensive) so that was good news – I also spoke to all of my immediate neighbours about the application and invited them to ask any questions if they wanted and if they would like, to comment on the application – only two of them commented and both in support – winning!
In the meantime, there were some announced changes to ASHP rules for boundaries and also if you live in detached houses you can go from 1 to 2 ASHP’s – I spoke with the planning officer and kept the application running – just in case.
Planning was approved on the 20th December, so the process took around 6 weeks end to end, probably faster had I submitted the correct format drawings in the first place!
The report from the case officer was very detailed, and even down to the amenities that the house enjoys (corner position, near green space) so these are all things that need to be considered, especially if you’re looking to place a heat pump in view of the street.
Planning Application details:
Next Steps
At the time of writing, we’re waiting for an install date (and have been since the announced changes last month as Octopus wouldn’t put it forward until Planning Approval but the changes allowed that to move forward) and managing the cold as best as we can – luckily we have an immersion heater on the hot water tank which we have combined with a MyEnergi Eddi and that allows me to manage the times of heating water around low kWh pricing on Agile and we are using our log burner in the living room a lot as well as the AC units in the bedrooms.
