A study commissioned by the telecoms regulator Comreg has concluded that the increased use of materials such as foil-layered insulation as well as aluminium and PVC window frames in the construction of homes had led to a reduction in already poor indoor signals for mobile phones.

The study, which was carried out in collaboration with Aalborg University in Denmark and Queen’s University Belfast found such materials could reduce signal strength by between 100 and one million times. That was the effect of a reduction in radio signals of 20 to 60 decibels (dB).

They carried out tests on PVC, aluminium and hardwood windows and found between 15 and 45 dB additional power loss, with higher levels for aluminium and PVC materials.

Insulation resulted in additional power loss of 15 to 60 dB with the highest levels found in material with metallic layers. Foil-backed plasterboard reduced signal strength by 45 dB while plain plasterboard had little effect. Polyiso rigid foam with a thickness of 150mm resulted in 55 dB loss of signal.

Among brick materials, only cavity blocks had any significant impact by lowering signal strength by 25dB while roof materials had only a small effect.

“The building materials which caused the most radio attenuation were those used in heat insulation, especially those with one or more foil layers, and windows, especially triple-glazed windows with aluminium or PVC frames,” ComReg said.

The telecom regulator said the situation could become worse as building and insulating materials become more energy efficient.

“Depending on the chosen materials, type and age of the building and the frequency of the radio wave, the resulting total attenuation could easily be sufficient to make it impossible for mobile handset to operate effectively,” ComReg said.

It claimed the problem could be addressed by the use of mobile repeaters or using fixed broadband connections.