What is the most energy-efficient conservatory roof?

Jun 14, 2023

With energy prices rising over the last 12 months, you’ll pay anywhere from 66% to 129% more to heat your conservatory with an electric heater today than back in February 2022, which could tip your heating bills into the red!

One way around this is to insulate your conservatory, meaning it takes less energy to get up to temperature and stays warmer for longer. While there are several solutions to insulate a conservatory, from thermal blinds to floor insulation boards with underfloor heating, the best results are offered by upgrading to an energy-efficient conservatory roof with a low U-value. The reason is simple – warm air rises, so inefficient roofs leak enormous amounts of heat, costing you money and leaving you unable to enjoy your space. However, not all conservatory roofs are equal. This article reveals the most energy-efficient conservatory roofs, with expert advice to help you transform your space for the better.

U-values and conservatory roofs

We use U-values to measure the thermal efficiency of conservatory roofs. The lower the U-value, the better insulated the roof is. W/m²K is the unit in which the U-Value is measured. W/m²K stands for Watts-per-metre-square-Kelvin. You can use U-values as a benchmark for conservatory roofs, although if you go too low, you can reach a point where the cost-to-benefit ratio fizzles out.

Here are the typical U-values for the most common roofs:

  • Polycarbonate (25mm) – 1.6 W/m²K to 2.1 W/m²K.
  • Glazing – 1.5 W/m²K and 2.3 W/m²K.
  • Insulated (solar control) glass – 0.50 W/m²K to 1.0 W/m²K.
  • Solid tiled roof – 0.15 W/m²K to 0.30 W/m²K.

Most conservatories in the UK have either a polycarbonate or glazed roof, offering relatively poor thermal efficiency compared to newer insulated glass technologies and the solid roof technology that is becoming increasingly popular. For reference, a solid conservatory roof typically offers a U-value of around 0.18 to 0.28 W/m²K, but the Leka Roof has a U-value of 0.15. That superior U-value comes from multi-layer insulation, which significantly slows down the rate of heat loss. Every layer and product element is implemented to not just suit its primary purpose but to be naturally more insulative.

Insulated glass versus solid tiled conservatory roof – which is best?

The heavyweight title for the most energy-efficient conservatory roof pits insulated glass against a solid roof. So, which is best?


If you want the most energy-efficient conservatory roof with the lowest U value, a solid roof is superior to insulated glass by some distance. While the Leka roof has a U-value of 0.15 W/m²K, insulated glass typically has a U-value down to 1.0 W/m²K. In this example, the Leka roof is 147% more efficient than insulated glass, giving it a win by knockout. Why is it so much more efficient? Windows lose heat through conduction and convection, where the inner panes absorb internal heat and transmit it to the outside panes. Solid roofs have thick, multi-layer insulation to prevent this.


While the U-value of a tiled roof is superior to insulated or solar control glass, their composition has different effects on warmth. A solid roof will trap more heat you produce with an electric radiator or heater and keep your conservatory warm for longer. In contrast, an insulated glass roof allows a small solar gain, heating your conservatory with the sun. Tiled roofs are warmer in the winter and cooler in the summer unless you have lots of sun in the winter, in which solar gain comes into play.


Both solid tiled roofs and insulated glass roofs are suitable for south and west-facing conservatories where overheating is likely. Unless your conservatory is shielded from the sun in a north or east position during the day, an insulated roof is essential to make it usable. Solid roofs are superior to insulated glass for outright heat and solar gain rejection, allowing zero solar gain. However, insulated glass does a good job.


Solar control glass can eliminate up to 90% of roof glare from the sun, a considerable improvement over standard glazing. It can make your conservatory usable in the summer and transform your space in the winter. A solid roof eliminates up to 100% of roof glare from the sun, depending on whether you have Velux windows or skylights. It will make your conservatory feel like any other room in your home by shielding the sun’s rays.

Light levels

Insulated glass lets lights through, albeit less so than standard glazing. Some solar glass reacts to the sun’s intensity in real time, becoming darker to reflect light and heat, making your conservatory a pleasant space. A solid tiled roof will block 100% of the light from above without a Velux window or skylight, bringing your conservatory windows to the fore. The effect is simple – light levels are like those in a heavily glazed living room. Ultimately, light levels are sufficient with both roofs, although solar glass will be brighter when measured side by side. Whether this is more desirable depends on the extent of your window glazing and where your conservatory is.


Solid roofs use lightweight roof tiles to match the appearance of your house tiles. The Leka Roof uses Tapco slate or Metrotile & Britmet tiles, which are recyclable, suitable for all pitch angles, and guaranteed for 40 years. Most people prefer the appearance of a solid roof because it makes their conservatory look like an extension rather than a bolt-on space.


The cost of any conservatory roof varies depending on the type, size, and location of the conservatory and the quality of the materials. Solid roofs typically cost around 30% more than insulated glass roofs, meaning £5,000 becomes £6,500, and £8,000 becomes £10,400. For the extra money, you get a superior U-value and a roof that gives your conservatory the looks and feels of a traditional extension. Therefore in the long running paying that bit extra could end up saving you thousands of pounds.

Summing up

When it comes to the most energy-efficient conservatory roof, a solid tiled roof easily trumps insulated glass. The Leka Roof offers superior efficiency with a U-value of 0.15 W/m²K, captures and traps more of the warmth produced by an electric heater, eliminates more glare, and keeps your conservatory cooler in the summer. However, some people prefer the look of a glazed roof, and insulated glass does allow a level of solar gain, which can benefit conservatories with minimal exposure to the sun a bit better due to the sun’s heating qualities. Ultimately, both roofs will adequately create a comfortable temperature in your conservatory throughout the year, but solid roofs are best for outright energy efficiency.