Conservatory heating is a necessary expense if you wish to use your conservatory in the winter months or Autumn/Spring on overcast days or in the evenings. The are many different ways to heat your conservatory and we will look at some of them here, investigating the relative pro's and con's of each method including purchase prices, installation costs and running costs where possible. Below is a summary of some of the methods of heating your conservatory along with approximate costings on the assumption of a 10m2 area. Assumes 2kW heating requirement and average electricity tariff of 12p. Running cost is when on and not annual average.
Conservatory Heating Method
Fan heater
- Cost - £10
- Running costs - 24p
Oil Filled Radiator
- Cost - £30
- Running cost - 24p
Electric panel heater
- Cost - £150
- Running Cost - 24p
Night storage heater - economy 7
- Cost - £175
- Running Cost - 9p
Connect to existing home central heating system
- Cost - £250
- Running Cost - 9p
Split unit air conditioning system as heater
- Cost - £500+
- Running Cost - 24p
Air source heat pump + under tile heating
- Cost - £2150
- Running Cost - 6p
Reasons to heat your conservatory?
- Maybe you use your conservatory as a breakfast room in which case it needs to be warm in morning all year round.
- If you conservatory is used throughout the day during Winter it is a good idea to have a heating solution that either has a very constant temperature or can be topped up during the day if required.
- Perhaps you keep sub-tropical or tropical plants in it which could not withstand the freezing temperatures we get in the winter here. Then it must not drop below a certain temperature.
Electric conservatory heating Pro's
- No ventilation needed
- Quickly adjust the temperature
- Easy to adjust
- Clean
Con's
- Running costs can be high
Gas conservatory heating Pro's
- Low running costs
Con's
- Ventilation required
Domestic central heating system
You could simply connect a new radiator to an existing central heating system. Check with your conservatory supplier or local building officers to make sure this is allowed. If you have an efficient boiler already then this method will have a very low running cost. It is a requirement that the radiator you place in the conservatory has its own thermostatic control and can be turned off. For optimum heat circulation it is suggested to install the radiator near the dwarf wall though this is not always possible nor indeed convenient.
Pro's
- Cheap to run - estimated 9p per hour for 2kW of heating assuming high efficiency boiler and heat transfer system in house.
Con's
- Cost of installation ~ £250 including labour for a single radiators
- Heating during the night
- Many people turn their central heating off during the night and so this will not help frost protect and plants you have in there.
- Control of temperature may be an issue depending on how the thermostatic control of heat in the rest of the house is set-up. Your house and conservatory will heat up and cool down at different rates.
Fan heater
Go out to Argos or whoever and buy a fan heater
Pro's
- Cost ~ £10-20 for a 2kW unit
- Portable
Con's
- Noisy
- Air flow can be irritating
- High running costs ~ 24p per hour for 2kW of heating.
Electric panel heater
Buy and install a simple low profile electric panel heater.
Pro's
- Easy to install- plug it in
- Fairly low cost ~ £150
- Plenty of heat available - up to 3kW per unit
- Quick to heat up
- Slim line
Con's
- Running costs can be high ~ 24p per hour for 2kW of heating.
Oil filled radiator
These are also available from 'most good retailers'
Pro's
- Very cheap ~ £30 for 2kW unit
Cons
- Not slim line
- Heavy to move
- High running costs ~ 24p per hour for 2kW of heating.
Night storage heater
Although not as vogue as they once were they are still available widely and now they are much more slim line than the huge brick filled blocks they used to be.
Pro's
- Can operate of economy 7 ~ 9p per hour for 2kW of heating during the night.
- Fairly low cost ~ £175 for 2kW unit
Con's
- Can be expensive to install
- Not easy to regulate
- Expensive to 'boost' ~ 24p per hour for 2kW of heating.
Tubular Heating
This is commonly used in outside rooms, sheds and greenhouses where the desire is to prevent the room from going below zero which could damage plants, pipes and other items.
Pro's
- Frost protection kits available.
- Designed to operate in damper conditions e.g. glass house or garden shed.
- Splash proof if conservatory used for lots of plants that need watering.
- Cost ~ £20-40 including frost thermostat
Con's
- Low power only really usable for frost protection
Free standing gas fire
A calor gas heater is an example but an be either butane or propane depending on design.
Pro's
- No installation costs
- Portable
- Cost ~ £125
Con's
- Can be bulky
- Heavy to move
- Sometimes smell
- Cause condensation
Heat Pump
Heat pumps come in two varieties air source and ground source. This defines where they extract the heat from. Heat pumps are commonly used as the source for a under floor heating system due to the low temperature water they produce. Air source heat pumps also use systems with a fan on the interior heat exchanger to blow warm air in. They operate using the refrigeration cycle. The inside of a fridge is cold and the back heat exchanger is warm. In a heat pump the outside world is cooled down and the heat is pumped into the inside. The advantage is that typically for every 1 unit of electricity 4 units of heat can be brought inside.
Pro's
- Can also be used as a cooling means
- Can be wall or floor mounted.
- Low running costs ~ 6p per hour for 2kW of heating assuming 4 to 1 heat gain.
Con's
- Generally expensive
Ground source heat pump Pro's
- Able to better extract heat in very cold weather from the environment than air source
Con's
- Almost certainly too expensive for conservatory cooling unless considered as part of a larger change in central heating system or in a new build construction.
Air source heat pump Pro's
- Not as expensive as ground source ~ £1500
Con's
- Still expensive
Conservatory under floor heating
Pipes are run either underneath the tiles or within the floor screed. These pipes carry a working fluid that can be heated thus heating the floor surface.
Pro's
- Comfortable way of heating a room
- Invisible
- Doesn't take up any space
- Can be powered off central heating, heat pump, gas or electric source
- Low running cost even with electric as usually find ambient temperature can be lower and still comfortable.
Con's
- Installation cost ~ £350 for install in 10m2
- Cost ~ £250-300 for 10m2 kit under tile
- Cost ~ £200-250 for 10m2 kit in screed
Air conditioning
Either a portable unit with vent to outside world or a split system professionally installed and wall mounted. Air conditioning units are usually selected on their cooling capacity rather than their heating capabilities. Therefore running costs are tricky to calculate.
Pro's
- Obviously is good for cooling as well
Con's
- Noise
- Cost ~ £500+ for split system
- Cost ~ £250+ for portable system
How much heating do I need?
The amount of heating required depends on
- Size of conservatory
- Insulation properties of the glass/frame - U value
- Required temperature differential - temperature inside to outside
Heat loss is modelled using the following equation
Heating required (watts) equals U value * Area * temperature difference
Area is the glass area of the conservatory plus 1/3rd of the area of the connecting wall. It gets more complicated if the conservatory is constructed using different glazing options (e.g. roof) or is angled. So for a conservatory with a 10m2 floor area and 2.4m high walls and slightly sloping roof one would have an area of 37.3m2.
Single glazing has a U value of around 5 or more. Old style double glazing is about 3. Newer low-e coatings are closer to 2 with triple glazed argon filled (read expensive) units as low as 0.4!
Assuming you wish to have a minimum temperature of 18C in the daytime (with say an outside temperature of zero) we can then calculate the required best case heating requirement at about 2kW. With low-e glass it would be about 1.3kW.
Note: A dealer of conservatories or heating unit will be able to input more realistic figures but this is just ballpark. It allows us to compare different methods of heating the conservatory for price on a very typical size conservatory.
It's clear that a good way of heating your conservatory is to stop any heat within the structure escaping in the first place. However, extremely high performance glass (such as tripled glazed argon filled low-e variety) can be very expensive and depending on your conservatory usage you may never recover the investment in reduced heating bills.
Conservatory Heating Conclusions
There are a few different ways of heating your conservatory. Typically the lower upfront cost the higher the running cost. Ultimately its a hard call as to how much to spend on well insulated glass and how much to spend on efficient heating systems. Hopefully this breakdown of methods and costings has given you the information to make a better informed decision.
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