Mon, 25 May 2026 04:10:05 +0100 https://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18380 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18380 Fri, 05 Dec 2025 17:11:27 +0000 tony
The big news is that my dream is about to come true

I would be keen to from any others who have heat flux data for walls of any type please]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18350 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18350 Sat, 13 Sep 2025 15:34:59 +0100 jam295
A couple of years ago, we bought a two-storey 4-bedroom 1890 detached Victorian house in north-west England (108 sqm footprint, 350 sqm wall area) in need of substantial rennovation. We have replastered, replumbed and rewired the interior and it is now heated by a modern gas boiler and radiators, with wet underfloor heating for the kitchen-diner area. The exterior was rendered long ago, and the rendering is in extremely poor condition and needs to be replaced. At the same time as replacing the rendering, we are trying to decide whether to also add external wall insulation (EWI), as the walls are currently uninsulated. We would use breathable external wall insulation, and prefer a natural product such as wood fibre. We have quotes for (uninsulated) Ksystem TC15 Silicone Solo for the render (base, mesh, primer, silicone), which is marketed as "breathable".

The house has "early cavity walls", so the cavity is only a few cm, and not wide enough for cavity wall insulation. We decided not to insulate internally due to worries about condensation forming in the walls. There is a loft, and a cellar under the front of the house.

I have used the SapJS calculator at https://openenergymonitor.org/sapjs/ and entered our building's properties, as best as I can estimate them. The modelled annual heating energy usage is about 48,000 kWh, which matches our actual annual usage (measured from gas bills) to within about 8%. I am somewhat skeptical that this is not a fluke, due to all the uncertainties involved, but for the moment let's assume it is roughly right. The model predicts 42% of total heat loss going through the walls.

I used a current U-value for the walls of 1 W/m2K, based on the different layers (inner surface, plasterboard, timber battens/gap, inner leaf, air gap, outer leaf, render, outer surface). Bringing this down to 0.3 W/m2K with EWI to meet building regulations would reduce total heating energy usage to 33,000 kWh, and save about £1000 per year.

Our motivations are not purely financial; we would also like to reduce our energy expenditure for environmental reasons, so even if it took a while to pay back, we would probably still do it, so long as the upfront cost (over and above the existing project cost of rerendering) was not prohibitive.

Ideally, we would eventually like to install a heat pump and solar panels, but our understanding is that the heat pump would only be powerful enough if the house is well-insulated.

My concerns are:
- My modelling with SapJS is a lay-person's calculation, and I would like to get this professionally assessed. The important question is "How effective will the EWI be?", because if it does not save significant energy, it is not worth doing.
- The house has many other heat losses, e.g. from draughts and uninsulated suspended floors in the front of the house. Does this reduce the effectiveness of the EWI, or is this an entirely decoupled problem?
- The wall cavities open at the top into the (cold) loft, and there are air bricks in the outer skin for ventilation to reduce moisture in the cavity. If the walls are left like this, then hot air will easily convect out of the top, presumably causing massive heat loss. We could seal the cavities at the top and block the air bricks, but will this cause problems with moisture/condensation? Could the cavity instead be vented internally? Since the cavity will now be warm, as it will be inside the insulation, maybe this is not a problem? Alternatively, could we fill the cavities, since now that they will be warm, interstitial condensation shouldn't be a problem?

What sort of professional could I hire to give me the best advice, taking into account the particular nature of this old building, and all the "edge cases" that might be relevant to the decision? I have found companies who will do an energy assessment, but will this be careful and customised enough? I've heard that EPC assessments are often very rudimentary, and I need more than a basic tick-box exercise. Do I need an architect? Some sort of building engineer?

How can I know whether the EWI installer will take proper care of all the junctions and edges, which I understand are vital for avoiding cold bridges? Do they need to worry about interstitial condensation?

I would appreciate any advice that people here might have.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18016 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18016 Thu, 09 Nov 2023 11:25:22 +0000 revor whereas the energy "certificate" says it is 111 w. The label on the back of the TV says 347W bit puzzling but maybe that may be to cover other stuff one may plug in and take power off the TV.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18005 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=18005 Sun, 22 Oct 2023 14:48:28 +0100 Beau
I have been roped in to help a friend with a few energy audits. We are just collecting information from the sites and passing the info on to a contractor. I went for the first one last week with no training and don't think my friend has done much. Loads of info to collect some of which is not a simple matter like what insulation type/thickness is in walls and roofs (no access to either). I was a bit taken aback by the amount of guesswork involved and recorded to be taken as gospel!

If I am going to help again I want to do as good a job as possible as I see duff data as worse than useless.

I suspect some of you good folk know what's involved in doing a proper job and would very much like to hear what you think I should know.

In all honesty, I do not think it right how we did the job last week but if I don't I suspect someone else who doesn't give two hoots would replace me.

Thanks
Beau]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11107 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=11107 Wed, 04 Sep 2013 08:20:00 +0100 harper16 Does any one use thermal bridging modelling and if so, what can you recommend?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16112 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16112 Sat, 04 May 2019 12:58:45 +0100 djh
It looks professional and works out condensation and decrement delay and suchlike to EU standards.

It has an English language option, but only some of the content is in English. The rest remains in German. So if anybody with better German with me wants to have a go and see how useful it is, that would be helpful.

PS It might be better to use it before brexit, from some of the statements on the site about access within the EU.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17379 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17379 Sat, 05 Feb 2022 20:20:33 +0000 vord
I made a spreadsheet that takes the calculation steps from U value calculations through degree days through to energy use calculations.

https://www.the-salutation.co.uk/photos/u-value-calcs2.xlsx

It's not perfect. But I'm never going do anything more with it. Better to open source it to you lot to take it forwards.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17296 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17296 Tue, 23 Nov 2021 12:23:12 +0000 Dominic Cooney It's only a draft at the moment because it isn't quite finished yet, but I was delighted that it came out at a "B"

Better than the "C" that we got for the last place we did (of similar solid stone wall construction)

The only thing we could have done better on would be PV but the roof is East/West and I don't think we have any room inside for invertor(s) but I would not rule it out in the future.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17227 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17227 Fri, 08 Oct 2021 16:53:26 +0100 djh
https://www.simpleenergyadvice.org.uk/energy-efficiency/reduce-bills

I just filled in their assessment and it came up with complete rubbish suggestions! Fit a new gas main (that won't cost anything!). Replace my doors (200 year payback according to them). Fit solar thermal and solar PV. etc etc.

I'd be interested to know if it comes up with equally silly suggestions for other people or if it's just because I live in an unusual house.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16953 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16953 Mon, 01 Mar 2021 14:40:13 +0000 lloydroutley
i am a final year Building Surveying student at UWE and am currently carrying out some research regarding Energy Performance Certificates for my dissertation. I'm looking for home owners who are interested in energy efficiency within their homes to take part in a quick survey. I would greatly appreciate anyone who can spare a few minutes to take part!

You can find the link for the survey on the consent form here:

https://www.dropbox.com/s/ogiiny8pymsgqkr/Dissertation%20Consent%20Form%20-%20LR.pdf?dl=0

The following links are a privacy notice for anyone concerned about the safety of their data, as well as a participation information sheet providing more information about the research.

Privacy notice - https://www.dropbox.com/s/7pg7ok26f7896gn/Dissertation%20Privacy%20notice%20for%20research%20participants%20-%20LR.pdf?dl=0

Participant info sheet - https://www.dropbox.com/s/xcp6hm442cl2iz2/Dissertation%20participant%20information%20sheet%20-%20LR.pdf?dl=0

Thank you!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16783 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16783 Sat, 07 Nov 2020 15:56:19 +0000 tony
Unusually two regularly use spaces one a gym and the other a art area both remote from the other buildings and both with radiant electric heating.

In both cases I rejected the winter savings on heating, can you see why?

I have a very interesting semantic point on LED and it is true too --  when the energy rating of lighting is reduced less heat goes into the building as lost heat from lighting (saved on electricity bill) BUT in the heating season this heat was reducing the demand from the heating system and so not all of the savings attributed to LED are genuinely available, there is often a cost saving but it will be the difference in cost between electrically produced heat and oil or lpg heat which is delivered cheaper per kWh output.
In the space with electric radiant heating there is no saving for changing to LED !!!!!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16743 Mon, 05 Oct 2020 20:51:05 +0100 jamesingram
A friends built a SIP house , 3G glazing , dont know exact wall, fabric thickness but I think its pretty low close to U=0.1 , individual MHRV in kitchen bathroom, PV on roof
Trouble is he's fittted a peat stove and it seems more problematically electric resistance heating rads. as a back up
though he wasnt expecting to use them much.
this has brought his SAP figure up too high for building regs sign off.
originally it was speced ASHP with UFH.
Anyone know the best bang for bucks to get it down.
Assessor told him he'd be better of with an oil boiler and rad with regards to SAP which seems odd given the carbon intensity of grid electric is falling to make it almost close the natural gas.
He's looking for a quick solution to resolve the issue.
I suggested just taking the electric rads out or switching to a couple of air/air heat pump units
thanks for any advice]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15688 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15688 Sun, 22 Apr 2018 22:36:05 +0100 RobinB
https://www.ofgem.gov.uk/sites/default/files/docs/drhi_essentialguidetooptionalmonitoring_v2_0_mar_2016.pdf]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2926 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2926 Wed, 12 Nov 2008 17:25:42 +0000 tony
So far at 250mm down it is 18.75 C and at 450 it is constant 18.5

I am doing a run at 750mm deep over the next 48 hours

With this very slow temperature gradient the rate of heat flow must be low I think and therefore the heat loss much smaller than generally accepted.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16276 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16276 Thu, 10 Oct 2019 16:19:02 +0100 vord
The previous SAP calculation used Build Desk and over-estimated energy usage by about 6 times (even after correcting to my degree days). That makes it not at all useful to me for prioritising improvements that might result in a real reduction in energy use. Instead it forces me to spend my budget insulating the mistakes in the calculation rather than work on the important stuff.

Is it normal for officially recognised SAP calculations to be so far off the mark?

Can anyone recommend a way to have a SAP calculation done that accurately represents the build level of the house at the moment. Some it insulated to passiv haus standards and some is still single glazed. It needs to be accepted by building regs but otherwise I would like it to be as accurate as possible. I'll provide a spreadsheet with dimensions, wall constructions, and the Lambda values for materials I have used.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16277 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16277 Fri, 11 Oct 2019 00:32:12 +0100 tony
I said steer well clear, replace the lights at your expense and you fully benefit from the savings.

Replacement scheme is priced at 45k

Lights on average 5 hours a day six days a week

Cost benefit analysis is my job and I want to include additional cost for replacing the “saved energy” with an allowance to generate the saved electricity with gas heating during the heating season.


They pay 10.5 p per kWh for electric and 6.2 for gas

Saved electricity £15k Gas heat in winter = £3.5k >> savings = 11.5k

Four year payback, why hasn’t it been done already?


Please pick holes]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15604 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15604 Mon, 05 Mar 2018 21:43:13 +0000 djh
http://www.enmanreg.org/degree-day-base-temperature/

There's also a bunch of other information about degree days and other topics on the site.

In the newsletter, it mentions a spreadsheet: "I'd like to thank regular reader David Bridger who sent me an Excel spreadsheet which, when given monthly consumption and degree-day figures to base 15.5C, will estimate the correct base temperature to use. I have his permission to distribute this with my training courses"]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16072 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16072 Tue, 19 Mar 2019 09:46:47 +0000 rytech Any On Construction Domestic Energy Assessors on here that could advise on any good sites for completing online CPD in relation to energy assessment? Thanks in advance for any advice.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15563 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15563 Wed, 07 Feb 2018 21:50:03 +0000 RobinB https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12521 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12521 Wed, 03 Sep 2014 13:39:59 +0100 Greenfish
Just had our door blower test run, not got results yet, but was underwhelmed by the experience. Pretty sure we are well within Part L requirements, but was hoping to get below 1 (units confused!) and have a chance to feel and listen for any tiny leaks. In the end the guy was happy things were "good enough", well of course they were, and the fan was on and off in minutes. More worrying he did not seal the MVHR input/output grilles, wish I had done it before hand. He said switching it off was enough, but I am convinced it seals just because the fan isn't running. Also the seal of the fan into the door didn't look that great, I could see daylight around the cracks (no tape).

So I will get a number, but not a true measure of what we have achieved, and no indication of the weak points. Was I hoping for too much?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12052 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12052 Mon, 05 May 2014 09:39:00 +0100 Harefield https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=15204 Sat, 29 Jul 2017 18:45:07 +0100 rytech
I am new here so please accept may apologies if I have posted this in the wrong place.

I wondered if anyone may have advice on how best to calculate the timber bridging factor where the
Engineer specifies the use of double studs? I make it as 2 x 38mm studs =76mm
600 cts - 76/600 = 0.127 or 12.7%
400 cts - 76/400 = 0.19 or 19%

The default factors within the U-Value conventions are 12.5% and 15% so the above seems a little low? Any advice would be gratefully received.

Many thanks,
Ryan]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13868 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13868 Sat, 05 Dec 2015 10:45:49 +0000 Shevek
Haven't had a chance to try it yet but I have my house retrofit fully modelled in Vectorworks so I'm going to take the chance to finally run the PHPP calcs on it. I'll let you know how it goes.

Marketing video:
https://www.youtube.com/watch?v=unjp-WuSL20

Article:
http://planet.vectorworks.net/2015/09/improving-energy-efficiency-using-vectorworks-2016s-energos-tool/

Help files
http://app-help.vectorworks.net/2016/eng/index.htm#t=VW2016_Guide%2FEnergyAnalysis%2FEnergos_Energy_Analysis_Module.htm]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14905 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14905 Sat, 11 Feb 2017 07:33:46 +0000 cjard
I'm sure he will also be interested in what I can learn from this thread

So I'm after doing some data logging.. Just not sure what I'll need to measure, and what with (product recommendations). You can assume I've got loads of spare computing power and ability to program them, I just need connectable hardware. I'm also not so flush with money at the moment, until I temortgae the place so the boss will turn down any outlandish purchase requests :)

Some weather station seems a given, temperature monitors for rooms, or maybe pipes. Electrical power consumption devices (clamp round cable type preferred, but I can also still cut the cable and joint it in as the cables leaving the CU are accessible..) might be required too?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14562 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14562 Sat, 24 Sep 2016 21:33:27 +0100 numenius
I encountered similar several years back when EPCs first appeared. Our then home was actually featured in the press and on the Energy Saving Trusts own web site as a good example... but when we came to sell it the EPC gave us a D! That came down to the fact we had a log fired heating system and the software in use was so rigid that it basically recognised mains gas on a housing estate type house and nothing else (for example such systems have pipestats, not a tank stat - but the software then only recognised a tank stat - so lots of points lost because it "saw" an completely unregulated heating system, and so on) - so I've never been a huge fan of this particular industry as the systems seem even now to be too rigid. Though thankfully found a helpful assessor who explained it all to me this time.

But it does make me think is this stuff really worth the paper it's written on?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14535 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14535 Wed, 14 Sep 2016 11:27:52 +0100 dicktc I am assuming this PV figure is based on the total predicted PV generation for the year. However why would it be multiplied by the standard price for a unit of electricity? Isn't this misleading?
If my PV system generates electricity when I'm out all day and there is no demand, then surely that electricity will be sold back to the grid at a considerably worse unit price than the price I have to pay to buy electricity, so in reality it won't offset my energy costs in the way the SAP report suggests.
Grateful for your comments if anyone knows about this.
Thanks]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14465 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14465 Wed, 10 Aug 2016 17:03:54 +0100 Daren

Any comments?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14365 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14365 Thu, 30 Jun 2016 16:17:31 +0100 delboy Looking for a SAP assessor for 11 flats.
They are change of use in existing building, previously office, now reclassified as residential.
Not sure if this is Part L1a or 1b.
Please let me know if you're up for it.
(they are in Banbury).
Thanks
Del]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14338 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=14338 Sat, 18 Jun 2016 17:17:10 +0100 tony
The standard was set up over thirty years ago and a lot has changed since that time. Within the next thirty years energy prices will have risen hugely.

What is the optimum energy demand for a building, is there such a thing and is it time or energy price dependant?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3290 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=3290 Tue, 13 Jan 2009 16:54:09 +0000 jamesbl https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13916 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13916 Mon, 28 Dec 2015 17:53:02 +0000 vord
For a completely uninsulated old solid brick house with 100mm insulation between rafters in the loft it comes up with:
Walls: 30%, roof: 12%, windows: 34%, floor: 23%

I have upgraded most of the loft to 300mm insulation. The heating upstairs (zoned and reasonably well controlled) no longer comes on at all. Heating bills appear to be less than half what they were immediately before I insulated (though it is very warm this winter). I am convinced the insulation has reduced heating by more than 8% - with that tiny reduction the heating upstairs would still be on but it isn't.

I think the issue is that heat rises. The SAP calculations (and my own) don't appear to take any account of this. How would you go about plugging the effect into your own calculation?

Or does anyone have anecdotal evidence that could prove my calcs that suggest insulating the ground floor but leaving the roof poorly insulated would have a far greater effect than insulating the roof and leaving the ground floor un-insulated?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2741 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=2741 Wed, 15 Oct 2008 19:13:58 +0100 10100
tia.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13658 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13658 Fri, 11 Sep 2015 20:45:35 +0100 Nick Parsons
Thanks.

Nick]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13654 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13654 Wed, 09 Sep 2015 19:45:23 +0100 Chris P Bacon
The immersion is 4.5kW, 3 phase, 400V and has a single cable of about 12mm diameter permanently wired via a safety switch box.

When I go looking for a monitor to do the job all I seem to find are units with 3 clamp on sensors each to be clamped on to a single phase normally at the consumer unit to measure the buildings total electricity use.

Is it possible to have a monitor with a sensor which will clamp on to the cable with all three phases combined in it or will I have to remove the sheathing from a length of cable so that I can place 3 individual sensors on to each phase?

Is there a better way?

I don't want to spend a load of money on this and don't want the expense of having to call in an electrician just for this although at some point in the future I will have one here to do another job but that may be quite a while from now.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13433 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13433 Fri, 12 Jun 2015 08:16:57 +0100 Triassic
Prieto and Hall used government data from Spain, the sunniest European country, with accurate measures of generated energy from over 50,000 installations using several years of real-life data from optimized, efficient, multi-megawatt and well-oriented facilities. These large installations are far less expensive and more efficient than rooftop solar-PV.

Prieto and Hall conclude that the EROI of solar photovoltaic is only 2.45, very low despite Spain’s ideal sunny climate. Germany’s EROI is probably 20 to 33% less (1.6 to 2), due to less sunlight and less efficient rooftop installations.

http://energyskeptic.com/2015/tilting-at-windmills-spains-solar-pv/

Makes you wonder how efficient the UK s PV installations are?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13247 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13247 Fri, 27 Mar 2015 16:45:12 +0000 NEF
To ensure we make My Home Energy Planner as useful as possible, we are conducting a survey to find out if you've ever previously assessed your home energy usage and what information you would like to be given when considering potential home improvements.

We want to hear from you, whether you own or rent your home, regardless of how much you know about energy. The survey takes about 10 minutes to complete and to thank you for completing the survey you can enter our PRIZE DRAW where we have 12 OWL Micro Wireless Energy Monitors to give away! Please complete the survey here: https://www.surveymonkey.com/s/7H8X8KV

If you have any questions please contact Alex on alexandra.steeland@nef.org.uk. The National Energy Foundation is a Registered Charity No. 298591. For more information, visit www.nef.org.uk.

Thank you for your time.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13251 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=13251 Sat, 28 Mar 2015 22:08:32 +0000 gravelld
I have written this up in full on my blog: http://www.elstensoftware.com/blog/2015/03/28/first-openbem-assessment/ (sorry this post is HTML so no linky linky)

Summary:

• SAP Rating: 68.5


• Annual Energy cost: £1589


• Floor 85.3 W/K


• Roof 27.9 W/K


• Walls 99.8 W/K


• Windows 168.5 W/K


• Ventilation 178.5 W/K

A few thoughts:

The ventilation figure is assumed given the data I entered. Until I get an air tightness test it can't be accurate, but I would not be surprised if it *is* the largest factor.

It surprising how much the windows appear to be losing. Conventional wisdom amongst many appears to be replacing windows does not derive large savings. I suppose it depends on a case by case basis.

Thermal bridges are ignored in SAP, right? So things I have such as the following will not be considered:

• Some (not many, thankfully) plasterboard walls (I felt a draught through a plug socket yesterday!)


• Unfilled external sides of cavity walls being brought into the thermal envelope following extension, the whole cavity then acts as a 'chimney'' into the loft (I've done a thermal imaging camera survey that showed this. Another blog post, when I get around to it)


• External walls bridging the thermal envelope into ground floor extensions

Do I need to worry about these types of things, considering I am not aiming at Passivhaus levels (we have neither the time nor the money to achieve this)? Let's say I have my eye on AECB Silver which would mean cutting our heat demand by about 60% per m². The trouble is that because they aren't considered in the model, I can't do a "what if" scenario to see if they make much difference.

What does SAP occupancy mean? The number of 3.1 seems low for a house of this size if it means the average number of people living in the house.

Is a fan-assisted flue (as we have on our oil boiler) the same as an open flue?

I have attached all the input data (it's JSON encoded but I had to name it txt to get it attached), all opinions appreciated.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12485 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12485 Mon, 25 Aug 2014 14:46:04 +0100 sl638e
It looks like we have to begin by getting an Energy Performance Certificate and a Green Deal assessment, and we may need some additional loft insulation to qualify for the scheme (borderline at the moment).

A search for assessors in the area brings up 90 results, some being companies I know already and don't fully trust.

The question is how to select a reliable company from these - one which will give me useful info and not try to sell me anything inferior. Does anyone have any tips on this?

Would you search for providers who install solar thermal, for example, or would you look for an independent assessor who isn't tied to any products or services?

Alternatively, would it be better to approach companies who install solar (and who come recommended to me) but who don't have any connection to the Green Deal scheme? I guess they might be able to put me in touch with people who can do the assessment, even though they don't offer it themselves.

Btw I don't expect that we will want to take up a green deal loan, although I'm not ruling it out. I'm only following that route in order to qualify for RHI.

Any help appreciated!]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12901 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12901 Tue, 16 Dec 2014 18:54:47 +0000 revor The house is a stone farmhouse but I made the mistake of externally insulating it to early we should have just done enough to get an EPC at the lower end then get the generous RHI and insulate later. Seemingly had we not externally insulated, the house would have been classed as a pre 1900 house the RHI would then have been very generous, but the Green Deal assessor has told me that the EPC would take into account the external insulation which puts the house in a completely different category.
We have added an extension with wider cavities at double the Building regs requirement. We do not have a SAPS because it is not new build and because we have not finished the build cannot get an EPC and the assessor has stated he cannot do one until the heating system is installed, but at the moment I cannot determine the best system to put in. If I could calculate the Specific Heat Demand ( Kwh/sq.m/year) of the completed house then I can use this in an RHI calculator which would give me a good indication of where to go with it. The company that designed the u/f heating system calculated from the u values I have supplied a heating loading of the system in Kw at -3 deg c ambient. Does anyone know how I can get from this figure to the Specific Heating Demand?
Thanks]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12847 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12847 Mon, 01 Dec 2014 10:12:28 +0000 andyman99 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6574 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=6574 Thu, 18 Nov 2010 17:18:45 +0000 James Norton
Although we would do the traditional SAP and SBEM calcs for building regs the goal is to use a tool that will inform the design process and add some more quantative data to our overal consultancy service.

We are only a small team so can't afford big cash and would only probably need one seat, it would need to be pretty user friendly and allow us to get some presentation info off it (or the data that we could feed into a chart software package), and would need all the basic stuff including renewables contribution etc.

Any ideas...?

J]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12756 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12756 Thu, 06 Nov 2014 15:58:19 +0000 atomicbisf
Can this number be trusted at all?

Ed]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12666 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12666 Sun, 12 Oct 2014 08:49:30 +0100 Greenfish https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12498 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12498 Fri, 29 Aug 2014 00:30:42 +0100 bogal2 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12489 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12489 Wed, 27 Aug 2014 13:33:04 +0100 DaffyLizardChunks
After much research into building physics I am very confused about how to do this. It is is thermal bridging but none of the calculation methods that I have found seem appropriate to me. It also seems increasingly likely that I will need to find a modelling programme which I would rather not do.

Can anyone help?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12472 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12472 Fri, 22 Aug 2014 23:38:59 +0100 tony
Do they realise that all that energy finishes up inside the homes as heat? the majority of vacuuming happens indoors during the heating season and only a very tiny proportion outdoors with the energy totally wasted.

I think it would be a good idea if it was helping reduce energy use but is it? There are also downsides to not cleaning so effectively.]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12398 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12398 Mon, 04 Aug 2014 13:53:30 +0100 shuff27
Not coincidentally I've just received a mailshot from Home Survey Reports Ltd ('recommended partner' of my installer Ice Energy) offering to carry out the report for £200+VAT. It provides a sliding scale of increased RHI payments, starting at £302 over 7 years for an SPF of 2.7. This is based on a house using 20,000 kwh p.a.; the EPC for my house estimates demand at 26,000 kwh p.a.

Anyone in a position to advise/guesstimate whether my installation (Ecodan 14kw heat pump running wet UFH downstairs, domestic hot water, rads - rarely required - in bedrooms) is likely to have a SPF higher than 2.5?

And I wonder what this company actually does to produce its report - if it's anything like a SAP I expect not a lot!

Thanks in advance,
shuff27 (newbie member)]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9040 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9040 Mon, 07 May 2012 18:47:04 +0100 tony
Has anyone got any thermal imaging pictures of blobbed and dobbed walls in the winter or on windy days?]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12156 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=12156 Mon, 02 Jun 2014 11:40:06 +0100 RobinB I know they can't count all that invisible insulation and airtighness but they have been forced to put "solar and immersion" for DHW when in fact it's "Solar and ASHP" because the tick boxes don't allow two sorts of renewables on an EPC. Do you think this will cause problems with the RHI application for ASHP? Any way round it? The man who did the EPC says it cannot be changed.
thanks!
Robin]]> https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9640 https://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=9640 Mon, 01 Oct 2012 22:25:15 +0100 jamesingram
So got this figure for wood from steamytea 4.5kWh/kg
and this 4.2kw/kg for seasoned wood from http://www.nottenergy.com/energy_cost_comparison/
also seen estimate for kWh/m3 but can find it .
Ok I know it's a bit of a best guess area , but if you're interested in logging your energy use to compare to other forms of heating energy whats the best option ?

How about ,; I've a 5kW stoves, so if it's on for an hour, that's 5kWh used , is that to simplistic ?]]>