Millions of pounds of taxpayers’ money could be wasted as a result of dubious advice and the approval of ventilation products given under the Government and Energy Supplier (EEC) energy efficiency programme activity overseen by the Energy Saving Trust (EST).

This claim is made by John Davison, Managing Director of Airtech Environmental Systems, a ventilation and condensation control specialist who says “data supplied by some manufacturers to EST, upon which approvals are based, is technically flawed.”

Green procurement is becoming increasingly important to customers, especially in the social housing market, where there is a drive to improve indoor air quality and hence the health of occupants while minimising the damaging effects of condensation which can rot the fabric of a building. Far from being ‘green’ these ‘approved’ products could result in red faces at the government and the EST.

Independent tests on a particular type of single room heat recovery (HRV) unit, one of the products accepted by EST, have shown that it is very unlikely to be energy efficient in typical British weather conditions. Airtech maintains that existing data used to evaluate the efficiency performance of this equipment is flawed because tests were carried out to ‘free (still) air’ with no wind resistance and yet figures available from the MET office show that the average wind speed in the UK is about 5 m/sec.

Although ‘free (still) air’ is normally used to measure air flow in the ventilation industry it is misleading to apply this method when evaluating the energy efficiency of heat recovery and extraction systems.

Airtech commissioned its own independent tests from BeataFlow Limited, a leading British specialist ventilation/airflow R&D company, to examine the single room HRV unit known to have been approved by EST. These tests obtained similar results in ‘still air’ conditions with no wind resistance. However, when tested – even on boost – with an external wind speed of 5 m/sec no air whatsoever was extracted by the HRV unit.

The tests also showed that on boost with an external wind speed of 7 m/sec – a wind state that occurs frequently in the UK – the air flow through the unit would actually be reversed and blown back into the room unless it were (unrealistically) hermetically sealed. In trickle mode with an external wind velocity of 1 m/sec, i.e. barely a breath of wind, almost no air was extracted: at wind speeds of no more than 3 m/sec the air flow was again reversed and blown backwards.

Quite rightly the EST bases its energy efficiency reasoning on energy consumption and HRV units appear to perform well in this respect because energy calculations take into account claims that heat is recuperated and returned to the room. Overall energy figures reflect the cost of running the unit less the value of the heat returned.

However, for this to be true air has to pass in both directions through a heat recovery unit, otherwise known as a heat exchanger, before any heat recovery can take place. The problem is that in typical British wind conditions no air is actually expelled through the heat exchanger because the average wind speed in the UK simply blows it back. In reality, heat recovery during a 24 hour period could be negligible. Cold air would often be blown into the dwelling and this would be exacerbated by the air intake mechanism within the unit. Furthermore the HRV unit would be consuming electricity 24 hours a day.

Single room HRV systems should not be considered energy efficient or to have any significant impact on reducing condensation. “In fact one could say that far from being heat recovery ventilation units they are heat loss ventilation units” comments John Davison, who adds “For the EST to approve the use of single room HRV as energy efficient suggests a limited understanding of ventilation. If HRV units are adopted, especially in social housing, there is a real danger that taxpayers’ money will be wasted on installing inappropriate ventilation systems that are not as energy efficient as claimed and, indeed, could even result in increased heating bills for residents. The problem could be especially hard felt by families suffering fuel poverty. On top of this the incidence of damage to health and housing through condensation is likely to increase.”

This situation would not be so serious and potentially dangerous if it were not for the fact that the BRE (Building Research Establishment), a highly respected industry organisation charged with a responsibility for offering expert opinion, has advised the EST in a recent Energy Efficiency Best Practice in Housing (EEBPH) scheme and approvals due later this year will again flag up HRV units as energy efficient.

Airtech is already witnessing evidence of these recommendations being adopted and believes it is vital that the ventilation industry acts swiftly to question the validity of EST’s approval of HRV units.