Best Heating for a Garden Office: Warm Without a Huge Bill

Choosing the best heating for a garden office is really a question about running cost, because the heater itself is cheap next to the bills it racks up over a winter of daily use. Get it right and you can work in a warm room from November to March for a few pounds a week. Get it wrong, usually by relying on a plug-in fan heater in a poorly insulated room, and you can spend more heating one small space than the rest of the house. This guide compares the realistic options and, crucially, what each one costs to run.

Insulation comes first

Before you pick a heater, be honest about the building. A well-insulated garden room, with insulated walls, floor and roof and decent double glazing, holds warmth so well that a modest heater keeps it comfortable. A thin, single-skin summerhouse leaks heat as fast as you make it, and no heater fixes that economically. If your room is not properly insulated, spend the money there first, because it cuts running costs for the entire life of the building. Everything below assumes a reasonably insulated space of around 10 to 15 square metres.

Understanding running costs

Electric heating cost comes down to one sum: the power rating in kilowatts, multiplied by hours used, multiplied by the price per unit. At roughly 27p per kWh (around the Ofgem price-cap unit rate in mid-2026), a 1kW heater running for one hour costs about 27p. Run that same 1kW heater for four hours a day and you are looking at around £1.08 a day, or roughly £30 over a working month.

The key point is that most electric heaters are 100% efficient, so a 2kW panel and a 2kW fan heater cost the same to run for the same heat output. What separates the options is how well they deliver comfortable warmth where you need it, how much heat they waste, and how easily you can control them. The exception is a heat pump, which we cover last, because it breaks that rule.

The main heating options compared

Infrared panels

Infrared panels warm objects and people directly, like sunshine, rather than heating all the air first. In a small office where you sit still at a desk, that targeted warmth feels effective quickly and lets you run a lower wattage. Panels are silent, slim, wall or ceiling mounted, and easy to pair with a thermostat and timer. A 400W to 700W panel suits most desks and costs little to run for the hours you are actually working. For many garden offices this is the best all-round choice.

Electric panel and convector radiators

Modern electric radiators with a built-in thermostat and programmable timer are a reliable, familiar option. They heat the air, so the whole room warms evenly, which suits a room you move around in. Look for models with accurate thermostats and open-window detection, since precise control is what keeps the bills down. A 1kW to 1.5kW unit heats a typical insulated office.

Oil-filled radiators

Oil-filled radiators are cheap to buy and give a gentle, lingering heat because the oil holds warmth after the element cuts out. The downside is they are slow to warm up and tend to be higher wattage, often 1.5kW to 2kW, so running costs add up if you leave them on all day. They are a decent budget stopgap rather than a considered long-term fit.

Fan heaters

A plug-in fan heater is fine for a quick blast of warmth first thing, but it is the worst choice for all-day heating: noisy, drying, and the heat vanishes the moment it switches off. Treat it as a backup, not your main system.

Electric underfloor heating

If you are building or refitting the room, electric underfloor heating gives a comfortable, invisible background warmth with no wall clutter. It is best as a base layer, sometimes paired with an infrared panel for a fast top-up, and it needs to go in before the flooring, so it is a fit-out decision rather than a retrofit.

Air conditioning with a heat pump

An air-to-air heat pump, the same wall unit that cools in summer, is the one option that beats simple electric heating on running cost. Because it moves heat rather than generating it, it delivers roughly three units of warmth for every unit of electricity, so it can cost around a third as much to run as a panel heater for the same output. It heats and cools, which makes a garden office usable year round. The catch is the upfront price, typically £1,500 to £2,500 installed by a qualified engineer. If you use the room daily and want the lowest bills, it pays back over time.

So what is the best heating for a garden office?

For most people the honest answer is one of two things. If you want the cheapest sensible setup and you mainly sit at a desk, an infrared panel with a good thermostat and timer is hard to beat: low wattage, silent, and cheap for the hours you work. If you use the room all day, every day, and want the lowest possible running cost with summer cooling thrown in, an air-to-air heat pump is the better long-term investment despite the higher fit cost. Whatever you choose, a decent thermostat and timer matters more than the heater badge, because heating an empty room is where the money leaks away.

For more on making a garden room comfortable through winter, see the insulation and year-round guides on the Best Garden Room homepage, and check current electricity unit rates against the Ofgem price cap before you estimate your own bills.

Frequently asked questions

What is the cheapest way to heat a garden office?

An air-to-air heat pump is cheapest to run because it delivers around three units of heat per unit of electricity, but it costs more to install. For a lower upfront spend, an infrared panel used only while you work is the cheapest simple option, since it heats you directly at a low wattage.

How much does it cost to heat a garden office?

At about 27p per kWh, a 1kW heater running four hours a day costs roughly £1.08 a day, or around £30 a month. A lower-wattage infrared panel or a heat pump costs noticeably less for the same comfort, while a 2kW oil-filled radiator left on all day costs considerably more.

Is infrared heating better than an electric radiator for a garden office?

For a desk-based office, often yes. Infrared warms you and the surfaces directly, so you feel warm quickly at a lower wattage. An electric radiator heats the whole air volume more evenly, which suits a room you move around in. Both are 100% efficient, so control and wattage decide the bill.

How many watts do I need to heat a garden office?

For a well-insulated room of 10 to 15 square metres, a 1kW to 1.5kW radiator, or a 400W to 700W infrared panel over the desk, is usually enough. Poor insulation pushes that requirement up, which is why insulating the room first saves money long term.

Can I put a wood burner in a garden office?

You can, but it is usually overkill for a small room and brings extra work: a proper flue, heat-resistant hearth and clearances, plus you cannot leave it running unattended while you focus on work. Most people find electric heating or a heat pump far more practical.

Do I need to leave the heating on all day?

No. A timer and thermostat that warms the room shortly before you start and holds a steady temperature is cheaper than leaving a heater running flat out, and far cheaper than reheating a cold room from scratch several times a day. Controlling when it runs is the single biggest saving.