EPC calculation... again...

[Steven Prentice]

Just been looking through the forum for info about Energy Performance Certificates (EPC) and SAP wondering how they are calculated.

In my mind it could be a spreadsheet almost with tick boxes to get the score "Does it have low energy Light bulbs" - Tick - One point, "Does it have 100mm underfloor insulation" Tick - 2 points, does it have 200mm underfloor insulation, Tick, add another point and so on.

So... and not wanting a professional, legally binding, sell a house based on the report report kind of thing, is there any -free- software out there, or on one of your drives that I could access to give me a good indication of how my house is?

It seams weird you see that (in the case of my parents as an example), you can live in a house for 30 or more years and not be able to see if any of the improvements over that time have had an effect, but also in my case whether topping up the loft insulation or the under floor insulation (both about the same cost, same stuff you see) which would be have the most benefit.

So hoping to get some positive results here. Not too keen on point scoring and bickering that sometimes happens in forums, just a straight up answer "Try this"....

(and for those who do this for a living, not tying to steal your job, the same as knowledge of how to wire a plug isn't going to steal an electricians job)

 

[Swwils]

The SAP is a complex calculation and whilst it can be simplified to tick boxes wouldn't be very accurate. Even doing a SAP correctly on a box shaped house is not easy.

The BRE released several worksheets to explain the process, SAP software and Excel sheets are available on Google.

If your SAP calc is for Part L compliance, your BCB will most likely only accept them from a licensed EA.

Official SAPs can audited by the EA body like STORMA but this relies on the correct information and evidence being given to the EA for their calculations to be based on.

So, if you do not know how well your house is constructed or have evidence to show you at each individual element and junction then your SAP will never be accurate and only ever "indicative".

The current SAP score is also weighed with things like solar PV and other measures, when many will argue the elemental recipe and airtightness are much better real world performance issues.

Ultimately if you were to sell your house and energy's use was a concern to the buyer you could just show them the "scores on the door" a utility bill.

 

[^woody^]

It's all common sense. Use less energy, use more energy efficient components, insulate more, seal draughts.

Heat rises, so that's where insulation achieves more.

Your parents will never know if improvements done thirty years ago have been effective unless they log their energy use and costs daily and do everything exactly the same every day whilst factoring in the daily weather - and compare that with an alternative scenario as a baseline.

 

[oldbutnotdead]

Get one done and find out- several companies advertising online for less than £50. Be interesting to see if 'fitting a new condensing gas boiler' still carries a big fat positive score
EDIT Yes it's a tickbox exercise, the character doing it won't be doing smoke tests for draughts or anything specific like that, just looking at the basics.

 

[cdbe]

I'm not sure anyone would admit to producing these pointless reports for a living.

Do you want to save the planet or save money? The list of things to do to save money is short, but longer if you DIY. The list of measures to "save the planet" is long and eyewateringly expensive.

Start by putting the £50 you don't spend on the EPC towards things like draft proofing, hot water cylinder jacket, loft insulation top up, low energy bulbs, TRV's.

Don't get a smart meter, unless you don't understand that running your oven for 5 hours a day uses a lot of energy, the cost will just be hidden in your future energy bills. Surprisingly, the jury is still slightly out on whether replacing an ancient 40 year old boiler is going to save you anything!

 

[noseall]

Be interesting to see if 'fitting a new condensing gas boiler' still carries a big fat positive score

We've had our Vaillant combi with VSmart programmer a little over a year now. Just paid the latest bill and our history shows that the last four years' bills (gas and electric) are...
2021. £1572 (new boiler)
2020. £1698 (old boiler)
2019. £2059
2018. £1805

It's made a huge difference to our consumption and the way the house is heated.

 

[oldbutnotdead]

We've had our Vaillant combi with VSmart programmer a little over a year now. Just paid the latest bill and our history shows that the last four years' bills (gas and electric) are...
2021. £1572 (new boiler)
2020. £1698 (old boiler)
2019. £2059
2018. £1805

It's made a huge difference to our consumption and the way the house is heated.

I'm not disagreeing -similar experience at a previous home. More to do with the intended ban on fitting gas boilers to new builds, not seen 'fit an ashp' on any EPC recommendations yet...

 

[Steven Prentice]

several companies advertising online for less than £50.

Which is my thinking, if you can fill in boxes online with the info, then anyone -should- be able to survey their house well enough to produce a credible online result.. and if the home owner only needs to fill in simple boxes then surely the calculations behind that can be simplified.

No doubt a professionally produced report will use complex software

So to my question, looking for an indication of how my house performs and yes, I can save the full survey fees for actually doing work to make it better. Not interested in selling the house, or meeting the current regs (it did that when the house was built years ago)... just to see how it performs




I suppose I can go on the EPC website, and browse some houses with the recommendations and list what they are and the gains you get from doing that as a start.... but that sounds like a lot of work if someone knowledgeable has a link to a good resource out there

 

[oldbutnotdead]

Think you'll have to put in the hard yards yourself..., end of the day an epc isn't an accurate representation of how much energy your particular house is losing- it's a statistical average.
Cheapest and best payback comes from roof insulation- but even if you already have 270mm up there you can still improve by sealing all gaps between upstairs rooms and loft (pipes, cables, loft hatch). Also get some insulation right at the edges of the ceilings- you often can't go full thickness cos you'll block the eaves ventilation but 100mm is much better than nothing.
Next one is low energy lighting. If you have tungsten downlights still they are complete energy hogs- my sister was horrified when I pointed out her massive beautiful high ceiling kitchen with 15 x 50w downlights was using 750w per hour.
Next one is draught sealing- go round all your doors and windows with a smokey taper. And ground floor rooms at skirting board height. Put something behind the letter box to stop it leaking cold. Secondary double glazing (timber framed with polythene sheet on) looks a bit poor but can make a massive difference- we had it back in the 60s, it kept the chill off the bedrooms. Draught strips on timber doors, adjust laminate or upv doors so the seals work properly.
There are more but those are your starters.

 

[Steven Prentice]

Think you'll have to put in the hard yards yourself..., end of the day an epc isn't an accurate representation of how much energy your particular house is losing- it's a statistical average.
Cheapest and best payback comes from roof insulation- but even if you already have 270mm up there you can still improve by sealing all gaps between upstairs rooms and loft (pipes, cables, loft hatch). Also get some insulation right at the edges of the ceilings- you often can't go full thickness cos you'll block the eaves ventilation but 100mm is much better than nothing.
Next one is low energy lighting. If you have tungsten downlights still they are complete energy hogs- my sister was horrified when I pointed out her massive beautiful high ceiling kitchen with 15 x 50w downlights was using 750w per hour.
Next one is draught sealing- go round all your doors and windows with a smokey taper. And ground floor rooms at skirting board height. Put something behind the letter box to stop it leaking cold. Secondary double glazing (timber framed with polythene sheet on) looks a bit poor but can make a massive difference- we had it back in the 60s, it kept the chill off the bedrooms. Draught strips on timber doors, adjust laminate or upv doors so the seals work properly.
There are more but those are your starters.

Thanks. Normally when I want to ask a question the answer is rarely "Here is a handy link for you", but sometimes I don't ask the correct question and miss an answer.

Yup. I could go with a spreadsheet, meter readings, and a thermometer to work out how much energy my house is using and for what (you will still need to do the same even with a smart meter)... I know that immersion heater overnight is 2kwh for example (however with a log burner the space heating is trickier to work out). That won't say what advantages each proposed improvement will make.

So to get a nice spreadsheet. I'll have to do the thinking myself, which is what I thought.

Fully agree with what you say, get the minimum insulation and seal the gaps and work from there. Low energy bulbs when they need changing apart from the main 3 or 4 which are on for hours each day in the winter (say the hall cupboard, on for 1 minute twice a day will never save it's cost by throwing out a working bulb for example). For the letter box.... squirting some silicone sealant around the edges after the post has been on Saturday around, cover with clingfilm and shut the flap down hard creates a near perfect seal. Let it dry to Monday morning and trim