The push to improve building energy efficiency must not come at the cost of reduced indoor air quality, says Darren Finley, director of Vaillant’s air conditioning division
The Chinese air conditioning market has been depressed of late, the avalanche of electrical appliance buying seen across that vast country slowing to a relative trickle, according to recent reports.
However, Beijing alone still has 600,000 central plant air conditioning systems and in the run up to this year’s Olympic Games in the city they are coming under intense scrutiny.
The Chinese National Disease Prevention and Control Center has uncovered the alarming statistic that 99% of the ac units serving 3,000 Beijing hotels, restaurants and office buildings are failing hygiene tests. Less than 1% have been cleaned recently enough to allow them to comply with tightening air pollution standards.
So the authorities are getting tough. Any public place that wants to get its hygiene license in time to cash in on the influx of visitors for the games will have to have its air conditioning inspected and cleaned by May 31.
China has, of course, had big problems with airborne infections like SARS, which raised the importance of having hygienic ac and ventilation systems. However, the Chinese government has also noted the implications for energy efficiency and quotes research showing that improved maintenance will cut running costs by 12%.
In this country, the oil crisis in the 1970s placed energy conservation top of the priority list and buildings became better sealed as a result. However, the unforeseen consequence was a dramatic increase in sick building syndrome caused by plummeting indoor air quality.
We cannot afford for history to repeat itself and, like the Chinese, building owners and operators must be made aware of the need to improve indoor conditions while also driving down energy waste.
Supporting evidence
The advent of Energy Performance and Display Energy Certificates this year will focus greater attention on energy saving. However, there is no point having a building that is rated ‘A’ for energy, but is the equivalent of a ‘G’ for comfort as that will have a hugely detrimental impact on the productivity and well-being of occupants.
Humans spend something like 90% of their lives indoors and breathe almost 25,000 litres of air every day. Lower work performance is frequently symptomatic of poor indoor air quality in offices and schools, and asthma and allergies are more prevalent than ever.
Research carried out at the University of Denmark for the American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) last year showed that poor ventilation rates in classrooms were actively hampering the ability of children to learn. Better air quality, lower temperatures and increased ventilation rates could improve learning performance by as much as 20%, the Society showed.
The evidence supporting wider use of well-designed ventilation and air conditioning in heavily occupied buildings is overwhelming. However, with Part L of the Building Regulations calling for pressure testing of buildings to reduce air leakage, but Part F insisting on higher levels of fresh air for occupants the industry has a dilemma. Or has it?
The hygiene/energy efficiency connection
There is a common connection between ventilation hygiene and energy efficiency: Planned, strategic service and maintenance. Improving the standard and frequency of maintenance will not only reduce air contamination, but also cut energy waste.
Basic physics shows that as the resistance of a ventilation system rises the pressure drop also rises. As components like louvres, grilles and filters accumulate dirt and contaminants from the passing air stream their resistance will increase, so increasing the pressure drop.
Fans will then need increased power to overcome the additional resistance, provide the required fan pressure and continue to meet design airflows. Not only will the required fan power rise as systems become more clogged (or air flow reduce if the fan remains at the same speed) the active components within the systems such as dampers and cooling coils will be adversely affected.
A dirty cooling coil is partially insulated from the air stream so affecting its performance. Higher refrigeration costs may be incurred to compensate, but even more seriously, coils can be a major source of biological contamination.
As air passes across the coil, water condenses onto its surface and is collected underneath. Any particulate matter that escaped the filter is effectively washed out – including organic debris – turning this into an ideal breeding ground for bacteria, mould and algae. Under such favourable conditions, these microbes multiply rapidly to form large colonies. The moving air then circulates the microbes throughout the system and into occupied spaces together with their reproductive spores, the waste products from their metabolic activity and any toxins they produce to protect themselves.
Failure to adequately provide conditions that safeguard the health of occupants puts building owners and operators – quite rightly – at risk of litigation under the Health & Safety at Work regulations.
On top of that, insurance firms often use poor maintenance of ventilation extract systems as grounds for fighting claims made after fires or following employee health problems because they can assert that warranties have been breached due to lack of proper cleaning regimes.
Meeting your statutory obligations under the Workplace Directive, COSHH and the Health and Safety regulations is basic good practice, but does not have to be regarded simply as something that you have to do just to satisfy legislation. There are many long-term positives. Apart from the health benefits and improved productivity from more comfortable staff, energy bills should also fall dramatically.
Many ventilation fans, for example, churn around for years carrying the extra weight of dirt built up on their surfaces – once they are flowing freely again it takes up to 35% less energy to make them move. And clean equipment lasts longer because of reduced wear and tear on bearings. Planned maintenance saves money.
The market is entering a critical period as legislation and Corporate Social Responsibility agendas increase the need to improve energy efficiency, but budgets are also coming under pressure from the economic slowdown. Too often in the past we seen service and maintenance programmes being the first things to go when building owners look around for budget cuts.
This was never wise, but will become even less easy to justify if buildings are to meet their energy targets and cut emissions while still keeping occupants safe, healthy and productive.
Vaillant
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