Green Building Forum - GSHP Carbon footprint Tue, 19 Dec 2023 08:20:19 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 GSHP Carbon footprint http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284605#Comment_284605 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284605#Comment_284605 Sat, 14 Nov 2020 10:21:51 +0000 revor GSHP Carbon footprint http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284607#Comment_284607 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284607#Comment_284607 Sat, 14 Nov 2020 11:56:41 +0000 WillInAberdeen
If someone flogs you a 'hydrogen ready' gas boiler without
including a 'hydrogen-ready' gas meter, then it's just a methane boiler!

https://www.sgn.co.uk/about-us/future-of-gas/hydrogen/h100-nia/domestic-metering-solution]]> GSHP Carbon footprint http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284610#Comment_284610 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284610#Comment_284610 Sat, 14 Nov 2020 13:18:30 +0000 Ed Davies
Posted By: revor… and how about the embedded energy used in making the HP.
To a very rough approximation, the cost of an item can be used as a proxy for its embodied energy. Not terribly accurate but it gives an idea particularly when the things are made of similar materials, are about the same size and made in similar factories, such as an oil/gas boiler or a heat pump. An oil or gas boiler is, I think, likely to cost something in the region of £1000 whereas a functionally equivalent air-source heat pump [¹] will cost about twice that assuming you don't bother with the MCS BS.

Given that heat pumps are probably still priced a bit higher as being less mass-market items that would indicate that the embodied energy is likely no more than about 50% more than that of an equivalent fossil burner, if that much. By the time you take into account the extra infrastructure needed to support combustion (oil tank or gas pipes) it seems to me it's not likely a difference worth worrying about.

[¹] probably a bit lower power and running at a lower temperature (at least for space heating) but expected to run for a somewhat larger fraction of the day.]]> GSHP Carbon footprint http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284641#Comment_284641 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284641#Comment_284641 Sun, 15 Nov 2020 17:50:29 +0000 revor
https://www.carbonfootprint.com/calculator.aspx

and filled it in and was alarmed when it came out at 8.1 tonnes until realised it is shared between 2 of us. There is no way to input things into the calculator one may do to lower footprint, other than do less of the stuff that contributes to the CO2. e.g I have planted about 400M of hedgerow grow veg sell at gate to locals. The total CO2 for the house is 1.6 tonnes CO2. Hopefully before long should be generating from our PV and will contribute an estimated 5229Kwh annually and save 2.75 tonnes CO2 somewhere. If I substitute the LPG for a GSHP with COP of 3 my house CO2 comes down to 1.1 a saving of 0.5 tonne. The cost of my Solar PV is roughly about the same as would have cost me for a GSHP not including the RHI which probably would not get, as would have, like everything else, put my own in anyway. So solar PV is a far better contributor to reducing my CO2 than HP by a big factor (5.5). Also interestingly I could save 0.45 tonnes pa by becoming vegetarian. Swop car for EV save another 1.6 tons less whatever C footprint of the EV is. All this off course dependent on how realistic the calculator is.

An advantage of my LPG boiler is I can run it for short periods of time as can get 27kw into my thermal store when I want quickly, and just heat top part of store where the DHW HE draws water off. A 5 to 10 min burst is enough and would take one standard immersion heater 9x as long. I think will stop beating myself up by having gone the LPG route.]]> GSHP Carbon footprint http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284647#Comment_284647 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284647#Comment_284647 Sun, 15 Nov 2020 20:12:37 +0000 WillInAberdeen
Edit to add: that website allows you to overwrite the g/kWh with up to date figures. If you input 0.17kg/kWh, then 5229kWh of PV would save 0.89t of CO2.

Then they calculate that 1000kWh of LPG contributes 0.21t of CO2 whereas a GSHP (COP4) using 250kWh of electricity contributes 0.04t of CO2, so an 80% reduction. This is all in line with our previous discussion.

Further edit to add: your house has excellent insulation and you are using remarkably little LPG, you certainly should congratulate yourself not beat yourself up! A GSHP would be overkill for such a low heat load.]]> GSHP Carbon footprint http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284662#Comment_284662 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=16786&Focus=284662#Comment_284662 Mon, 16 Nov 2020 10:53:39 +0000 revor