Performance figures for REHAU Awadukt

REHAU Awadukt Thermo ground-air heat exchangers, monitored on projects since 2008, are returning impressive performance figures.

REHAU has been datalogging the performance since 2008 to gather real time data about how effective they are in pre-tempering ventilation air.

The figures are extremely impressive with monitored projects in Germany, France, Poland and the UK all reporting performance figures which exceed those predicted by REHAU's own GAHE software.

The results have now been published by REHAU and are available to download from the website.

The REHAU Awadukt Thermo system operates by drawing ventilation air into a building through underground pipework grids buried at a depth of around 1.5m.

The optimised polypropylene material used for the pipes maximises heat transfer between the ground which is at a fairly constant 7-13C and the incoming air, with the result that the air can be pre-warmed in winter by as much as 9C and pre-cooled in summer by up to 14C.

A low energy cooling system suitable for Passivhaus projects, REHAU has demonstrated that Awadukt Thermo can achieve a coefficient of performance up to 20 for commercial projects and 50 for residential applications.

In the UK, the monitored installation was in a domestic property linked to a MVHR system for optimum performance.

Sensors were installed in the air inlet tower to measure incoming air and just ahead of the MVHR unit upstairs and have recorded reductions in summer air temperatures of 12C and, more impressively, an 18C increase in winter.

During a major renovation of REHAU's head office in Erlangen, Germany, a GAHE grid was installed to supply pre-heated and pre-cooled air.

This summer, the peak temperature reduction was 12C (ie from 27 to 15C).

And, in France in a commercial office installation, the temperature of the air entering the building was typically reduced by a maximum of 16C in summer, which was then fed into the summer bypass of the HRV unit.

Steve Richmond, Business Team Leader for REHAU's range of Renewable Energy Products, said: 'Our studies show that the REHAU Awadukt Thermo actually considerably outperforms our estimates'.

'We have further detailed analysis available on each of these case studies for use by consultants and specifiers and can also offer a RIBA and CIBSE approved CPD on ground - air heat exchangers if required'.

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