SuperHome Database

Oxford, Belvedere Road

House Summary

Martin Crane

House Type:
1930 semi 2 floors + loft conversion

Carbon saving:
66% - SuperHomes Assessed  

  • Oxford SH
  • Wood stove

Measures installed:

  • Condensing boiler
  • Double Glazing
  • Draught-proofing
  • External Wall Insulation
  • Floor Insulation
  • Loft conversion
  • Loft Insulation
  • Low Energy Appliances
  • Low Energy Lighting
  • Solar PV Panels
  • Solar Water Heating
  • Water Saving Devices
  • Wood Stove

Upcoming events

Early interest in Open Days encourages SuperHome owners to host more events. If you'd like to visit this property please contact the owner and let them know. SuperHomers are often happy to respond to questions about their refurbishment project by email between times. Please read ‘more on contacting this SuperHomer’ before you make contact.

What visitors are saying

"The homeowners put a lot of time and effort into showing us around and explaining and answering our questions. We were there for an hour and gathered a lot of useful information."

Personal story:

Energy efficiency and renewable energy is my job and interest and I’ve always enjoyed a bit of DIY. So the natural progression of this is that I’ve done things to improve the insulation etc in all the places I’ve lived. Professionally I get to see lots of the renewables / energy efficiency technology and I sometimes feel it too complicated and so I like to test if the simpler approaches work eg thermosphyon on the wood burning stove which means no pumps to power or go wrong and no controls to go wrong. Work has given me access to dataloggers etc so I have been able to try to measure the effectiveness of what I’ve done.
Finally got a grant and decent price for external wall insulation in autumn 2015, so 90mm of expanded polystyrene + rendered finish was installed (rather slowly) over the winter of 2015/2016. Cost £7181 and a grant (Green Deal Home Improvement Fund) contributed £3750. The £7181 was lower than other quotes I’d had, and from a company that gave me more confidence + the grant made it very good price. The benefit is not just about lower heat losses but it’s stopped mould growing on the walls of the small room on the north east corner of the house. I’m pretty pleased with the EWI installation done by the InstaGroup. The scaffold gave me access to the roof and enabled me to install another 1.6kW of PV – which as I did it myself gets no feed in tariff. The PV have individual Solar Edge micro inverters which have worked very well – the data shows the range in output from the different modules which each get a different amount of shading. I had installed first SMA sunnyboy micro inverters which didn’t work (the literature says they work upto 240W module output but the output voltages were too high from my 230W modules, my 210W and 190W modules – the literature didn’t clearly state that – a frustrating waste of time and money).
Also installed a small heat recovery ventilation unit to extract from the bathroom but a secondary benefit was to push some slightly warmed fresh air into the coldest room that had a history of mould growing on the walls. This ventilation and the EWI seem to have solved this problem.


Not quite sure where my motivations come from but I have strong memories of visiting Centre for Alternative Technology when I was 10 and A level projects, my degree, MSc, work have all been energy efficiency related.
I think there is something rather nice standing under a hot shower knowing the water has been heated by the sun. A homely home should be warm all the time I think and I’m hoping that once the solid walls get their external insulation the house will have fairly high thermal mass, from the solid walls, and that running the stove each afternoon and evening in the winter will warm up this mass such that the house stays fairly warm during the other times of the day when the stove is off.
We do like the financial savings, the feeling of being a bit self sufficient on energy / water and do believe the the CO2 savings to be important.

Also see:
Property background:

1930’s and it took quite a while before I realised it was solid wall – which I wouldn’t have expected for a 1930s house. House still had it’s original steel window, I do like our new wooden double glazed ones but it was bit sad to remove the original window which were still in good condition. There was a 15-20 year old small flat roof extension to the kitchen and a much more recent loft conversion.

Key changes made:

By my calculations the peak heat loss for the house when we moved in was about 9.1kW – this is the fabric loss and in the text below I’ve indicated what I calculate each improvement has saved. The improvements will also have had quite an impact on reducing the draughts – but this is much harder to calculate – so I haven’t!

Building the single story rear extension has has a big impact on the space in the house and although much larger than the small extension it replaced it reduced the peak heat losses of the house by 1.3kW (based on 20C inside and 0C outside). The new windows throughout (apart from loft conversion windows) has also made a significant difference in heat loss (saving 1.4kW same basis as above) and draught reduction. I’ve spent quite a lot of time sealing up holes to try to reduce air leakage – but it’s difficult to know the impact, I really wanted to do a air leakage test before I started but not sure who to borrow the kit off (many years ago I did such testing for work…). The woodburing stove (with back boiler) is wonderful (installed professionally) as is the solar thermal (installed by me). The house awaits external wall insulation (EWI) which should save about 3.7kW. The new windows were installed in a position for the EWI to work well. The Green Deal was supposed to be supporting EWI – but I don’t think it’s going to deliver for this winter (if I known how long the Green Deal was going to take we might have gone with the quote I got from a not wholly reassuring EWI contractor 2 years ago). Insulating the solid wall I’m hoping will not just make the house warmer but also reduce the mold growth due to the condensation that occurs as the walls are so cold..
Heating system
I installed a new condensing gas boiler Remeha Avanta (all but the gas installation) and moved quite few radiators around – some big radiators came out of the rooms that now have under floor heating and I did some shuffling around so that most of the rooms have larger radiators than they did have, also changed the position of the TRV to the top of the radiator – the result is that we can run the heating at a lower temperature and still get sufficient heat out of the radiators to heat the room, the lower temperatures mean we get the full efficiency benefit of the condensing boiler. The underfloor heating (installed in on about 50% of the downstairs floor area) is supplied with the water than comes out of the radiators, there is no separate pump for the underfloor heating system, this saves a pump (and it’s electricity consumption) and lowers the temperature back to the boiler even more – to around 25-30C giving us about a 10% efficiency gain over a radiator system sending 60C back to the boiler, the other benefit of this type of boiler (not a combi) is that they are smaller and boiler runs continually when heating (the minimum output of this boiler is 6kW) and so there is much less cycling on and off of the boiler which has quite an impact on boiler efficiency in practice. At our old smaller house the combi boiler had a minimum output of about 12kW and when the heating was on the boiler would cycle on and off rather frequently as radiators couldn’t emit 12kW.
Rainwater harvesting all DIY and uses a 12v pump to supply water to WCs and washing machine. The 2 IBC (1m3 tanks on pallet bases) cost about £80 on ebay. The 12v battery to for the pump runs off a battery charged by solar and also a few other things like the broadband router run off this 12v batter too.
PV – 1.3kW installed by me with the mains connection and commissioning done by a MCS certified installer.

Measures installed in detail:

  • New wooden double glazed U1.4, draught stripped
  • 8m x 2.4 of external insulation done in 50mm PIR. 60mm PUR installed below DPC
  • Eaves topped up to 12″
  • Suspended floor now have 100mm Rockwool insulation installed between joists, all but 7m2 of solid floor has 100mm Kingspan
  • Draught-proofing throughout
  • Mechanical ventilation heat recovery extractor installed for bathroom
  • New condensing boiler, weather compensating controls. All new TRVs
  • 2m2 of evacuated tube with 250 litre thermal store and variable speed pump
  • 1.3kW of PV + extra 1.6kW added 2016
  • CFL or LED lighting throughout
  • Low energy appliances throughout
  • Water saving devices includes; rainwater collection, 2000 litre storage, rainwater to new low flush WC and washing machine. 12V water pump with battery and PV
  • External Wall Insulation 90mm of expanded polystyrene
Benefits of work carried out:

House is warmer – I’ve been monitoring the temperatures and now the house cools down slower over night – which I hope is due to the reduced heat loss due to the better insulation and draught proofing measures. I think the wood burning stove heating the large hot water tank up and the warming up the chimney breast actually means we’ve more stored heat that is released after the stove goes off.
The combination of solar thermal and wood burning stove means we really don’t use the gas for heating and hot water that often. Mind you house isn’t always at 21+C…!

Favourite feature:

Solar thermal – the collector oversized compared to what the conventional wisdom suggests – but the cost of getting the collector 50% bigger is fairly small in the whole cost of the system. I’ve installed the collector at 45 degrees from the vertical specifically to make it more efficient in the spring/autumn and less efficient in the summer (I would have made it steeper but this would make it even higher and more visually intrusive). This angle helps get sufficient heat in the autumn and spring and helps reduce the over heating problems in summer. The collector is a fairly cheap Chinese evacuated tube collector and it’s efficiency does start to fall off as the tank gets over 70C – so that helps prevent over heating too. The pump station Resol FlowCon D HE has a variable speed pump which means when the pump runs it only alt 10 -20% speed. The monitoring work that has been done has indicated that the pump electricity consumption can make quite a large dent in the CO2 savings from solar thermal. This variable speed pump I’m sure really reduces the electricity consumption (I should monitor it….) I have a datalogger on this controller and it has shown up a few problems on the install / setup which might otherwise have taken quite a while to find out about – so that’s been useful. The thermal store (from Newark Copper Cylinder) is brilliant – mains pressure hot water but without a pressurised tank or any pumps and it’s easier to connect the stove into this so that the stove heat can be directed to the radiators. The stove is thermosyphon – which is a bit old school – and our excellent plumber Nick ( who did the stove installation put in the large bore pipework with minimum of bends and constant gentle rise to the tank so that the thermosyphon would work. We both spent quite a bit of time trying to find out design guidance for the limits of a thermosyphon design but without much success so we took the decision to install the pipe in the way that would maximise the thermsyphon effect and see how well it worked. It works wonderfully and I’m really happy as I don’t like pumps, they are always oversized – (so the flow would be larger than is needed which would mix the thermal store up, and so reduce the temperature of the hot water for the taps and stop the coldest water being at the bottom which get the maximum efficiency out of the solar thermal) ,the pump uses electricity, need controls, users need to understand the controls, if the power goes off the stove over heats….. The themosyphon avoids all this and some other issues there isn’t space to mention!

What I’d change – larger thermal store, install the gas boiler lower (ie downstairs) so I could directly connect it to the thermal store – which would then heat up really fast and with lower temperatures back to the boiler to keep it condensing. I’ve had to put the boiler through a coil in the store to stop the boiler flow coming out of the over flow on the header tank.
The Remaha gas boiler and weather compensating controls haven’t been perfect – I think the product is basically good but the manual not that helpful and some of the parts needed (eg temperature sensor for hot water cylinder) quite hard to get hold of. The weather compensating control kept turn the heating on despite the room temperature being warmer than what the thermostat was set at – which took me a year to work out during which time my frustration lead me to control the heating on the boiler on / off switch.

The lean to I built along the side of the house is quite favorite feature as it has two long walls to stack wood against, the wood drys well, there is sufficient space for nearly 2 years worth of wood – so most of the wood gets 2 summers of seasoning. It’s all easy to get to (close to back door and you don’t get wet if it’s raining) when the wood in needed. This is a key but sometimes overlooked requirement if you intend to make using wood as your main heating source as user friendly as possible. The lean to also houses all our bikes making their daily use easy and has a washing line that can be used on days when you think it might rain.

Project update:

Some more photos can be seen at

EWI done winter 2015/16
1.6kW more PV early 2016
MVHR from the bathroom installed early 2016
Much warmer house over the winter of 16/17 now all the insulation works are finished.

Updated on 16/09/2017

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Assessment types

SuperHomes Assessed

A home that has been visited and assessed by us and confirmed as reaching the SuperHome standard, which demonstrates a 60% carbon saving.

Homeowner Reported

Information has been provided by the homeowner about their home and energy use prior to the installation of measures and following their installation which demonstrates a carbon saving. This information has not been verified.

Remote Assessed

The homeowner has provided information on their home including what measures have been installed which has enables an assessor working on our behalf to assess their carbon savings. This home has not been visited to verify the measures installed.


This home has not been assessed, but the homeowner has reported what measures have been installed. It may be that this home is awaiting assessment.