We’re nearing the end of our first full week living with air source heating, so I thought I’d start EnergyNotes to capture what we find out as we go.
You can read about making the move to air source heating on my previous blog post.
Wow, so many manuals. So many settings. I’ve been trying to set aside time to read the key ones (many are for the installer) but to be honest I’ve not got to them yet.
It all felt a bit overwhelming at the start, like I was given a high-powered car to drive after one driving lesson. I think that’s an issue with some sustainability stuff; it expects everyone to be an evangelist and spend hours pouring over it all.
(Actually, I have become an evangelist and have spent hours pouring over it all)
The system interface is clearly the pride and joy of some UX person at Daikin with its groovy electric blue for highlighted settings (see below) but it set off my accessibility klaxon for colour contrast.
Luckily most of what we need to use we’ve got access to on the LAN interface/mobile app setup we purchased. So no trips to the garage to turn down the water boiler, or see how much energy we’re using during the day.
We picked a challenging week to start using our new system, with some sub-zero night-time temperatures, rain and howling gales.
We’ve found that our three bathroom extractor vents let in lots of drafts (strong enough to push a bathroom door open overnight!), and are worse than the chimney drafts we anticipated, so we’ll need to upgrade those at some point to help further minimise heat loss.
Above all else, we realised how desperately we need better loft insulation. Our new insulation work was scheduled in during the week, but a sneaky mouse invasion in our cavity walls meant we’ve had to postpone it and set traps in the loft.
Currently, the temperature difference between the ground floor and first floor is a couple of degrees, so we know there’s lots more to gain when this work is finally done.
We’re getting our heads around the switch and keeping a log of what we change and the difference it makes. Key learning points so far are:
We have lots of data from lots of sensors, but essentially much the same controls we had over a gas central heating setup, namely:
We made a novice assumption that we could start the first warming cycle at 5:00am, just like we did at our old house. This was far too late and we spent the day catching up with heating. We’re currently starting at 3:30am which seems to work well, and switching at 8:30pm to the lower temperature setting.
As it’s (currently) colder upstairs we’ve moved the thermostat there as a base reference point. That’s likely to move back downstairs once things are settled. Radiators downstairs are turned down to leave upstairs on full to help make up the temperature difference too.
We’ve had fun edging down the water temperature from 45 to 40 degrees day-by-day and watching the impact on energy use, reducing from 6kWh to 3kWh per day at its best.
I completely forgot about another default setting that heats up the tank to 60 degrees on a Friday night to kill off legionella bacteria, so this morning we had a scorching hot bath and both mourned the waste of energy as we had to put in cold water.
Recently we’ve started to close the gap between our daytime (comfort) temperature setting and night time (energy saving) temperature as we were giving the system too much work to do in the morning. Energy saving is fine, but we’re gonna be warm in our house!
Using these changes together we’ve been able to drive down our energy use by about 39% from the first weekend when everything was set at default, with a minor blip on the last day due to a mistake I made on the settings! That was helped by some warmer overnight temperatures too.
As we never actually paid for any of the oil we used at this house (we managed to run down what was left in the tank) we don’t have any comparisons with what a switch from oil looked like. But we do have all our energy bills from our old gas-fired system to compare with.
This isn’t really a fair comparison as we previously lived in a small, 2 bed terrace (5 rooms total) and are now in a 3 bed detached house (10 rooms total), so our heating demand is far higher. Also, terraced houses benefit from sharing walls with neighbours, which reduces heat loss. On the flip side its victorian building construction compares poorly against our relatively new build with more modern building standards. To a point, anyway…
Usefully, energy bills use kilowatt hours (kWh) to make comparisons easy, so I converted these to energy use per day to show the variance through the year. This gave me a pretty clear picture of the seasonal changes.
Getting energy use information from our Daikin system is fairly easy as it’s available at 2-hour intervals on the system display or (a bit more conveniently) via the app. The data splits between heating and hot water too, and does comparisons by day, week and year. A shame there’s no data export feature to let me play more with it…
Our average energy use this week has been 28.5kWh per day, which compares to around 44kWh per day for a similar period in the old house. Our lowest use this week was 22kWh per day.
We’re still running our heating above what it needs to be due to the loft insulation issue, so I’m pretty sure we’re going to drive that total figure down much more once it’s in, and once we get a better handle on all the settings.
One question I’ve been regularly asked is how much we’ve saved on heating bills. With only one week’s data, insulation work outstanding and atypical weather I’m not going to bite the bullet on that one just yet.
We’ve also not yet applied for our Renewable Heat Incentive funding yet as we’re waiting on our certification. This pays us a quarterly sum over the next 7 years to offset the costs. The Ofgem process and guidance on applying could do with some service redesign/content design attention as it’s way too complicated to encourage people.
But the killer is going to be the actual difference in unit charges between different fuel sources. Looking at our bills, gas charges were 2.89p/kWh compared to electricity now at 15.25p/kWh. That’s over 80% difference which I’d be surprised if we manage to achieve through efficiency improvements.
Before I post next time I’m going to: