Electric Heating Systems

In this second post on energy-saving benefits of Infrared heating we will look at total heating requirements in a room of a family house from October through March 2007 - 2008. A 600 W Redwell ceiling mounted heater was used.

The room was westerly facing a net volume of 30.5 m3 required 451 W heat and was fitted with a 600 W heater.



Over the October to March period, the data was recorded as follows.



Observations: as the Autumn season kicks in during October, the house temperature falls and is maintained at a fairly constant 21 degrees C with some fluctuations above 21 degrees and not a single fluctuation below 20 degrees.

Outside temperature falls to a minimum -8.1 degrees C. By and large, you can see the "Consumption kWh / day" curve follows the outside temperature fluctuations inversely. This shows that home insulation is not perfect and heat is required inside to compensate! (We'll write a separate post on insulation! It's important!)

Over the 5 month period, total energy required to maintain 21 degrees centigrade was 208 kWh which we calculate to be roughly £29.12 at 14p per kWh.

It is difficult making a direct energy/cost-saving comparison with other forms of energy (e.g.) oil since:

- The energy efficiency of oil depends on the type and age of the burner which in all cases become progressively less efficient with age;

- Electricity tarifs can differ over a 24 period (e.g. peak and nightime hours);

- Oil prices are not stable, reaching a peak in September 2008 of 66 pence and settling by the end of the year to about 40 pence per litre (but unlikley to fall back below 30 ppl going forwards and currently 33p). EX VAT.

- the way people behave with oil heating is different because they can typically see/hear the fuel being burned and are aware of its unit cost! So typically people tolerate greater temperature fluctuations between daytime and nighttime whereas the temperature in the Redwell house was maintained at a steady temperature;

- The generally accepted heating benchmark is 20 degrees, not 21, and any form of energy will cost proportionally more to heat a given volume above 20 degrees;

- People overlook the electrical cost of running oil heating itself (about £75 per annum for a 50kW burner depending on use).

(But you get the idea)

We can roughly say that:

a) Using our previous post (see "Energy Savings from Infrared heating") we can infer that at least 736.28 kWh of energy would be required for oil-based heating for this room.

b) Assuming the burner is new (less than 3 years), condensing, lightweight, you could be seeing 10.22 kWh energy per litre of oil (@88% efficiency) meaning you will require about 72 litres of oil. An 'old' heavyweight, non-condensing boiler can be as bad as 55% efficient implying up to 115 litres.

So?

At September 2008 fuel prices of about 66p per litre then the equivalent fuel bill would have been anywhere between £47.52 to £75.90 depending on the efficiency of the burner and not including the electrical cost for running the burner. A brand new, lightweight, condensing boiler at mid 2009 prices would just about wash its face but would still decay over time and be subject to price uncertainty.