We’ve done the research to ensure your pool is insulated properly

Most insulation materials available are unsuitable for use in swimming pools. Further, some insulation material currently sold for use in pools may not be and may never have been independently tested for purpose. This certainly isn’t the case with Thermapool.

Topic UK spent the last eight years working with UK universities, building institutes and swimming pool trade bodies to help us get a comprehensive view of how to prevent swimming pools from losing heat in order to develop Thermapool to be what we believe to be the most premium product on the market reflecting 'formula one' style product development.

We’ll spare you the science lesson, but this is what we discovered:

Heat doesn’t just escape from the top of a pool

It makes sense that heat evaporates from the top of a swimming pool. However, there are other areas that lose significant amounts of heat that are often not considered by builders. Whether the pool is above-ground or in-ground, the sides and bottom of the pool will still lose heat into the soil.

By fitting insulation to the sides and bottom of a pool independent research on Thermapool showed it prevents up to 86% of heat loss.

Insulation needs to be dry to be effective

Insulation materials used in general building construction are excellent at keeping heat in as long as they stay dry. Unfortunately, such materials won't do for insulating swimming pools because they become wet and lose their insulation properties.

This discovery led us to develop Thermapool insulation which is independently tested to be waterproof. Thermapool has been independently tested to keep its thermal performance for more than 40 years so we guarantee it for 25 years ensuring its insulating properties.

Fitting insulation  inside the pool is more effective than fitting it to the outside

You wouldn’t think it would make much difference whether pool insulation was fitted to the inside or the outside of a pool. Well it does: a 50% efficiency difference in fact! When pool insulation is fitted on the outside of the pool, only 41% of heat loss is prevented. Thermapool’s unique waterproof qualities mean it can be fitted to the inside of the pool and prevent a significant amount of heat from escaping into the soil. This finding came from an experiment on Thermapool by Anglia Ruskin university.

Pool insulation needs to be robust

Like a normal building, swimming pools can be affected by minor ground settlement causing them to crack. Unlike other pool insulation materials, Thermapool has been designed to withstand these minor movements as well as the incredible weight and pressures that water applies  to the walls of a pool. This means it can not only be used on the sides of the pool but also on the bottom. This means it can be used to insulate the entire pool.

Heat Loss From Swimming Pools

Professor Hassan Shirvani of Anglia Ruskin University, Cambridge is one of the country's leading specialists of heat transfer in fluids working with Rolls Royce Jet Engines and Jaguar on technical issues.  He has been working with the founder of TOPIC UK Ltd, Nigel Rose to analyse heat loss from swimming pools and to test Thermapool's thermal properties.

Shirvani and Rose believe the pool industry and its customers would benefit financially from more research  on the subject of energy loss and energy gains from swimming pools. Energy losses from the ground are relatively simple to calculate due to the steady state of the soil temperature. It is not so easy to calculate the benefits of solar energy gains from the sun's rays into a swimming pool - "the green house/solar heating of pools".  When energy is gained by the water from the sun it is heating the swimming pool free.

If you scuba dive you will know that the deeper you dive the darker and colder the sea becomes. This is because the sun's rays are absorbed by the water. As water is transparent it allows the rays to travel through it but, as it does so, it loses energy!

Commonly thirty percent of the sun's energy reflects off the earth's surface and goes back into the atmosphere. But a clear swimming pool absorbs 100% of this radiant energy and magnifies it!

Heat comes from many sources

Strenuous exercise can raise human body's temperature to as high as 41°C. In a municipal swimming pool operating at 27°C swimmers exercising would radiate heat at +14°C from their bodies into the swimming pool so will raise the pool temperature. At peak times, when there can be more than 20 adults exercising this is significant.

In the same way that eco buildings have been developed to reduce energy requirements and reduce running costs by making the most of the natural energy that exists around us (eg. south facing windows to make the most of solar gains Thermapool believes it is be a new energy saving technology helping to develop the swimming pool industry.

In 2008 TOPIC with help from Anglia Ruskin University, carried out tests on a domestic outdoor swimming pool to research the benefits of different heating methods, comparing types of swimming pool insulation, heat pumps, solar heating, solar covers, and insulated/safety covers.

.Pool Experiment shows Thermapool works without Pool Cover

These test swimming pools pictured here were not covered! Yet there is still a 7˚c temperature difference.

The two identical miniature swimming pools (500x300x300mm) were constructed and set into the ground to compare the benefits of insulation.

Both miniature swimming pools had a concrete and steel construction which was then tiled. One pool had a 14mm layer of Thermapool applied.




Both miniature swimming pools were heated for three days with a 1.2kW heat lamp fitted above the pools.   The pool on the right has 14mm of Thermapool on the floor and walls.  The differences to the pool water and the soil temperature clearly shows the benefits of Thermapool just using solar heating.

Significant heat gains are shown in the soil from the un-insulated pool and a 7˚c water temperature difference between the two pools.    


> 75mm of Thermapool will give a Thermal Resistance of 0.25 W/m².K

> 3.75m of dry clay soil will give a Thermal Resistance of 0.25 W/m².K

> 8.75m of rock soil will give a Thermal Resistance of 0.25 W/m².K

These diagrams are scaled to show the amount of energy conducted from the water into the ground from a 5m wide x 1.5m deep swimming pool.

Thermapool 75 mm thermal conductivity 0.029 W/m.K   75mm of Thermapool will give a Thermal Resistance of 0.25 W/m².K


Dry clay soil thermal conductivity 1.5 W/m·K area of conduction. 3.75 metres of dry clay soil will give a Thermal Resistance of 0.25 W/m².K


Rock soil thermal conductivity 3.5 W/m·K area of conduction. 8.75 metres of rock soil will give a Thermal Resistance of 0.25 W/m².K 


All of these examples comply with the new swimming pool building regulation. Thermapool complies and saves you money on heating your swimming pool water and doesn't let you heat the soil.

Thermapool is the only swimming pool insulation system on the market to be independently tested and accredited to insulate a swimming pool.