Breath of fresh air

Indoor air quality is a growing concern in Britain's buildings

Despite the apocalyptic predictions about global warming and increasingly hot weather, it has taken a global pandemic to bring greater focus on the topic of indoor air quality (IAQ).

Of course, consumers have been increasingly interested in heating, cooling and ventilation in their homes to improve their comfort levels, but when it comes to the health properties of the air they breathe indoors, it’s only recent events that have made people question whether their air really is fresh.

“The fact is that the indoor environment of our homes often is simply not up to scratch,” says Richard Soper CBE, former Worcester Bosch chief executive officer and Unico Systems representative. “With even more of us looking to improve rather than move, the changes and improvements made now will need to last much longer. Couple that with a fundamental shift away from office working and a changing climate that is seeing the UK experiencing record summer temperatures and it becomes clear that the way we heat, cool and ventilate our homes must take centre stage.”

The big issue

There are significant health factors when it comes to poor air quality. Aside from the threat of the COVID-19 virus, higher rates of hay fever and allergies mean that looking more closely at air quality is essential, particularly for vulnerable groups such as babies, children, the elderly and people living with respiratory issues and allergies.

“Social behaviour has changed and today people spend, on average, 90% of their time indoors,” says Amena Warner, head of clinical services at Allergy UK. “Our indoor environments are often poorly ventilated, causing humidity to rise, creating ideal conditions for mould and house dust mites to thrive in our soft furnishings and bedding. We are a nation of pet lovers, with our pets often living indoors which can also add to allergens in the indoor environment.

“A minimum of 9,000 deaths every year are attributed to indoor air pollution in the UK and indoor air levels of many pollutants may be up to 10 times higher than outdoor levels. We need to act now to protect future generations by working together to find solutions to improve the quality of the air we breathe in our own homes.”

The ongoing pandemic has raised the topic of standardisation around ventilation and air quality as people are being encouraged to go back into work. The British Medical Association (BMA) said measures should include:

• Greater guidance and support for businesses and educational settings to create sustainable, COVID-secure environments, as well as enforcement of standards.

• Emphasis on the importance of good ventilation, including setting legal standards. Financial and other support for businesses and educational settings must be made available to implement these requirements ahead of the autumn and winter period, when respiratory viruses spread more easily and buildings must be kept warm, limiting options for natural ventilation.

Commenting on the British Medical Journal (BMJ) report, Efforts to stop the spread of COVID-19 should focus on preventing airborne transmission, Dr Chaand Nagpaul, BMA chair of council, said: “The BMA has repeatedly said that there is strong evidence that good ventilation is vital in the fight against the spread of COVID-19 and the publication of this editorial from the BMJ shows just how crucial clean airflow is.”

Free flowing

There are several options to improve IAQ, with ventilation playing a key role. The most obvious solution is to simply open windows as fresh air dilutes and removes trapped air and contaminants from indoor spaces, helping to reduce the transmission of airborne viruses. However, this isn’t beneficial when located in highly polluted areas or for those suffering with allergies. Of course, it can also pose a security risk.

Mechanical Extract Ventilation (MEV) and Mechanical Ventilation with Heat Recovery (MVHR) systems are good options to improve IAQ as they actively extract air from wet rooms (kitchens, bathrooms, utility spaces) via ducting to a central ventilation unit which exhausts to the atmosphere.

“In the case of MVHR, there’s the added benefit of supply and extract ventilation combined as these systems re-use waste heat from the extract air and use it to efficiently pre-warm the fresh air drawn into the building using a heat exchanger,” explains Paul Williams, Domus Ventilation product manager. “The filtered, pre-warmed air is then distributed around the home, effectively meeting part of the heating load in energy efficient dwellings.”

Some models feature advanced heat exchange proficiency, enabling up to 95% of waste heat to be recovered and come with a 100% thermal (summer) bypass, which automatically activates when the air temperature reaches a pre-set level, allowing in cooler, fresh, filtered air without warming it through the heat exchanger.

MEV and MVHR systems provide good ventilation in addition to being energy efficient and effective at dispersing polluted air. These systems are best suited to new-build properties as they require extensive duct work. However, existing properties can use them cost effectively in bathrooms and kitchens.

“Energy recovery ventilators (ERV) are one of the best options for tackling IAQ long term,” says Soper. “ERVs reduce the cost of heating and cooling by capturing some of the heat from either the exhaust or the fresh air and can also be used to reduce humidity during cooling. When considering the value of an ERV installers, engineers and homeowners should consider climate, maintenance, and use when making their calculations.”

Pure quality

According to a study by the National Air Quality Testing Services, indoor air pollution inside UK homes is 3.5 times higher than outside. HVAC systems can only do so much as they tend to recirculate air from inside, with little dilution.

Although dilution will reduce some pollutants, such as gasses, it doesn’t help with larger contaminated particles in the air, commonly found in more urban areas. IAQ can be significantly improved when using filters and air cleaners with centralised HVAC systems as they have been designed to remove around 99.97% of particles. However, some HVAC systems can’t cope with high quality filters as they restrict airflow. Therefore installers should opt for ones that have been designed for high pressure drops that can easily incorporate higher rated filtration.

The fact that today’s homes are well insulated, coupled with external temperatures soaring, means that IAQ can suffer and record temperatures reached in the UK have left HVAC systems struggling to cope.

“Integration of heating and cooling means that temperature adjustments can be made through a central thermostat and the temperature in a building need only fluctuate between two to three degrees all year round,” explains Soper.

It’s not just about managing a building’s temperature either – humidity can make for uncomfortable living too. Whether it’s moisture from breathing, perspiration, showering or cooking, evaporation of moisture is an important factor when it comes to IAQ.

Individual dehumidifiers can be placed in each room to combat this issue, but it’s actually more cost effective to integrate humidification within the heating cooling and ventilation system that automatically adjusts the humidity in a room by cooling the air below the dew point.

“This is not possible with ductless cooling and is hard to achieve in a traditional duct system,” points out Soper. “If it is not up to the task, the occupants often decrease the set point of the thermostat until comfortable. This is wasteful and doesn’t always improve comfort. It can also lead to IAQ problems with mould caused by surface condensation and high humidity.”

It’s clear that a whole system approach is required to improve IAQ across the board, which should include air filters and purifiers as part of an HVAC system. However, it’s important that energy usage is taken into consideration when deciding on a preferred method to achieve good air quality.

Government policy

According to the government’s Ventilation and IAQ in New Homes paper, a large proportion of UK homes don’t comply with building regulations, with poor air quality found in homes that were tested. This either points to installers ignoring building regulations or poor interpretation of them. Industry insiders have cited the latter, asking for clarity and guidance from the government.

Building Regulations Part F of the Future Homes Standard, which will be introduced by 2025, covers ventilation and has recently been revised. It now recommends the use of MEV and MVHR for properties with any level of air tightness.

“This change has increased the minimum airflow through mechanical ventilation systems to each bedroom by 6 l/s as a result of concerns over insufficient ventilation in bedrooms overnight if doors and windows are kept shut,” explains Williams. “The revisions also included an increase in the background ventilation from 2,500mm² to 5,000mm² in extract-only systems. Natural ventilation systems, such as background ventilation, remain an option under the new regulations, but only for less airtight homes with a design air permeability of ≥ 5.

“Whilst external air pollution has been well studied, sadly, IAQ is a much under studied area. Our knowledge of the sources and worst effects of indoor air pollution is lacking.”

Industry impact

Ventilation could prove a lucrative line of revenue for installers as interest in solutions to improve indoor air quality are increasing in demand. However, training is essential for installers to understand how these types of system work, how air flows, when and where insulation and fire stopping material is needed, and which type.

“Installers need to be up to speed with Building Regulations Part F, which covers ventilation, and Building Regulations Fire Safety Approved Document B, both of which were recently revised,” says Williams. “One of the biggest issues in the ventilation sector is poor installation, which has a direct impact on the effectiveness of the ventilation systems, and changes to Building Regulations have been designed to address this.”

Training in ventilation systems design and installation is readily available. For example, the Chartered Institute of Plumbing and Heating Engineering (CIPHE) and Unico Systems’ heating, ventilating and cooling CPD can be accessed for free online.

As heating, cooling and ventilating in homes, businesses and shared public spaces has become an increasingly important issue to consumers it should be a major consideration for heating and plumbing engineers who stand to profit from this burgeoning sector.

Find out more about the free CPD from Unico for CIPHE members here.

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