A study by Leeds Beckett University shows a 24% reduction in heating bills following installation of floor insulation

17 December 2019

An in-depth study was carried out by Leeds Beckett University before and after Q-Bot installed insulation under the floor of an end-terrace bungalow in the North of England. It was found that applying Q-Bot’s underfloor insulation reduces heat loss through the floor by 77% and draughts by 39%, resulting in a 24% reduction in the Heat Transfer Coefficient.

 

In addition, the research demonstrates that measured U-Values, especially the pre-installation U-Value, is higher than the value calculated using rdSAP. This indicates that rdSAP is underestimating the heat loss through the floor.

 

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Details of the research:

 

The property was built in the 1960s with brick and block cavity walls, and has 44m2 of suspended timber floor. The study included:

    - Air tightness test - An air tightness test was performed before and after the installation according to the ATTMA Technical Standard L1 testing protocol, to measure the air lost through leaks within the house.

 

    - In situ measurements - A total of 13 heat flux sensors were attached to the floor within the property to measure the in-situ U-Value of the floor, using the average method within BS ISO 9869-1: 2014. Other sensors were also installed in the void, such as air velocity sensors, humidity sensors and thermistors.

 

    - Thermal imaging - Thermal images were used to identify key areas of thermal bridging and accurately measure a pre- and post-install indicative point U-Value for each thermal element.

 

     - Co-heat test  - Co-heating tests were performed according to Leeds Beckett Whole House Heat Loss Test Method to measure the thermal performance of the building fabric and estimate the amount of heat energy lost. The method uses electric heaters to maintain an even temperature before and after the install while recording the energy used. Finally, a weather station was set up on the outside of the property to adjust for external temperatures and solar gains.

 

Results:

 

The results show a 24% reduction in the energy used to heat the house following the install. The measured U-Value shows a significant improvement of 77% and a reduction in draughts of 39%. This has significantly improved the thermal performance and living conditions,  creating a warmer and more energy efficient house.

 

Measurement

Measured Floor Heat Loss (U-Value)

Floor Heat Loss calculated using RdSAP (U-Value)

Draughts (Air Permeability)

Total Measured Heat Loss (Heat Transfer Coefficient)

Before (average)

1.16 W/m2K

0.75 W/m2K

18.3 m3/m2.h @50Pa

177.7 W/m2K

After (average)

0.26 W/m2K

0.20 W/m2K

11.2 m3/m2.h @50Pa

135.3 W/m2K

Reduction (average)

77%

74%

39%

24%

 

Click here to view full report written by David Glew, David Johnston, Dominic Miles-Shenton and Felix Thomas.