Heating cost - currently 77.6 cents per day

We decided to turn on some heating on 30 October after the internal temperature dropped to 19 degrees. To begin with we switched on our underfloor heating circuits in the following rooms (all north facing)

1. Office
2. Utility Room
3. Main Bathroom
4. Master en-suite

Our living rooms are all south facing so they benefit much more from the direct solar gain. On sunny days simply opening the internal doors (along with the heat recovery) ensure that the solar heat spreads evenly around the house.

Each room has a 270 watt circuit connected to a Dev 535 controller which allow timed start/stop and temperature control (measure via floor and/or room sensor).

Our house has a dual tariff meter so we decided to switch the heating on from 00:00 - 08:00 each day with the termostats set to 21 degrees. This will ensure the heating will only switch on if the room temperature is less that 21 degrees.

We are on the ESB ValueSaver NightSaver price plan with the current prices
Cost per unit Day - 19.62 (Inc VAT)
Cost per unit Night - 9.70 (Inc VAT)

With all 4 circuits switched on the total power consumption is 1080 Watts or 1.08KW (a single unit of electricity) the cost for each night is 9.7 x 8 hours = 77.6 cent.

This is the maximum cost as with the recent spell of sunny weather the internal temperature hits 21 degrees therefore the underfloor heating circuits do not switch on.

Solar Performance

The Solar tubes supplied by Lars have been performing incredibly well. We have a 400 Litre Joule tank and Sun King 20-tube vacuum solar collector U-Tube (165x161x15cm/61kg). As of writing this article on 9th November we have had to use the immersion only twice for 1 hour to boost the hot water. With two small kids we use the bath frequently so the Solar is having to heat large amounts of water.

Autumn Update

16 October was the first day since the temperature dropped to 20 degrees.Since then the lowest internal temperature as monitored by the Boots sensor is 19 degrees.

Again the house was maintaining a very comfortable temperature.  I hadnt really understood the importance of solar gain. It is quite extraordinary as once the sun appears even if its only for a couple of hours it has a dramatic and long last impact. The internal temperature will rise to 21/22 degrees and the house will maintain this as the temperature start to drop outside.

This screenshot from my Oregon shows the temperature outside at 7:31 AM at 5.4 and inside at 20 degrees.

The worse days are the dull, cloudy and overcast days. There is little solar gain to be had so the house temperature doesnt get a boost. It also impacts he Solar Hot Water tank.