BSEE-JUL21-P16 Worcester Bosch_Layout 1 18/06/2021 10:38 Page 16
BSEE
Former Worcester Bosch CEO and Unico Systems representative, Richard Soper, outlines why heating, ventilation and cooling should be top of the agenda and how engineers and installers can ensure that they profit not just now but into the future.
he importance of Indoor Air Quality (IAQ) has never been greater. Tight construction can trap contaminants and keep air within internal spaces. Additionally, viruses do not easily dissipate increasing the likelihood of them spreading throughout the conditioned environment. A recent study in the Emerging Infectious Diseases journal identified recirculated air as a cause of Covid- 19 transmission within a Guangzhou restaurant. As a result, researchers have called for improved ventilation and temperature monitoring, as well as enhanced social distancing.[ii] From a Unico Systems perspective there is absolutely no reason why a traditional heating engineer more used to installing a traditional boiler and radiator system can’t adapt to these changing times and add both ventilation and cooling to their offer. It’s for that reason that, with the help of the Chartered Institute of Plumbing & Heating engineers we’ve now launched a free to access CPD course[iii] to enable this transition.
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A full system approach to IAQ
Ventilation, ventilation, ventilation
Ventilation is probably the best-known method of improving IAQ and is the first solution to incorporate. In fact, one of the latest recommendations from the Royal Academy of Engineering is for those who have split systems using only recirculated air to open windows when the system is in use. While providing an immediate answer for those in drastic need this is clearly not a long-term solution, as it means sacrificing heat and security whilst increasing energy usage. Energy recovery ventilators (ERV) are one of the best options for tackling this issue long-term. ERVs significantly 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. Anything that makes the HVAC system work less will save money yet lowering humidity to enable room occupiers to be more comfortable at higher temperatures is often an area that is overlooked. When considering the value of an ERV installers, engineers and homeowners should consider climate, maintenance, and use when making their calculations.
Integrated heating, cooling and ventilation systems are, without doubt, the best approach to tackling IAQ. Fresh air introduced into the home or business dilutes and helps remove trapped air and
contaminants in the home or office. In addition, viruses do not generally survive the outdoors, so dilution helps mitigate transmission from airborne viruses inside the building. In a small duct system such as Unico, heated or cooled air is passed through the air handling unit and can be easily configured to accept outside air before being distributed throughout the interior through small, heavily insulated ducts. To ensure constant circulation the system uses a process known as aspiration creating a gentle suction around the outlets that draws room air into the stream of heated or cooled air. This delivers draft free heating with a
temperature differential no greater than 1°C throughout a given space. As well as improving air quality the delivery system means that there is no need for space-consuming radiators as warm air is delivered into rooms via small spotlight style outlets installed into the ceiling.
Filtration
Even when providing outside air, most of the air in a HVAC system is recirculated from the indoors. A recent study by the National Air Quality Testing Services revealed that indoor air pollution in UK homes is 3.5 times worse than outdoor air pollution[iv]. Dilution does a great job of reducing some pollutants, notably gases, but doesn’t remove larger particles. This is where filtration comes in, particularly when the outside air is of low quality, for example in built up areas. One of the benefits of using a centralised system to provide heating, cooling and ventilation is that air quality can be significantly improved at any time of the year through the addition of filters and air cleaners. High Efficiency Particulate Air filters are the most common in the UK and are designed to remove at least 99.97% of particles from the air.
16 BUILDING SERVICES & ENVIRONMENTAL ENGINEER JULY 2021
The least efficient filters are designed to keep the HVAC system clean so that it heats and cools properly. These filters will capture the largest particles such as dust, hair, and dander. Better filters will capture smaller particles but will also create more air restriction which can reduce air flow and cause problems with the equipment. As a result, the type of blower in the system is an important factor in deciding what level of filtration to use. Most conventional HVAC blowers cannot tolerate much restriction and ductless mini- and multi-splits have no capability at all. Small-duct systems like Unico on the other hand are designed for high pressure drops and can more easily incorporate higher rated filtration.
Air disinfection
Disinfection is the process of killing pathogens and destroying viruses. There is only one known technology that can accomplish this while the occupants are in the room and that is ultraviolet light. It must be the right kind of UV radiation, however, and there must be precautions so none of the occupants are harmed. This type of disinfection has been used successfully for more 100 years in healthcare settings. Only recently, through Covid-19, has it become popular to use in a home or office. A UV light can be standalone whereby small fans pull room air into the device, exposing it to the UV light. These work well for a single room, but it is an expensive option for a whole building. A better solution is to install the UV light in the duct system. Air drawn through the ultraviolet lights destroy disease causing pathogens and microbes. This is particularly recommended for high risk areas such as care homes.
Comfort control
Although often overlooked as part of IAQ, maintaining a comfortable temperature for a home or building is essential. It is also one of the most important strands of Public Health England’s Beat the Heat: Coping with heat and COVID-19 campaign.[v] While in the UK, efficiency drives have increased the amount of insulation and widespread
radiant and underfloor heating means that we can easily achieve desired temperatures in the Autumn and Winter a series of record summers have found UK HVAC systems lacking in the hotter months. 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.
Thermal comfort is not just temperature however. People give off moisture though breathing and perspiration, even if sitting on couches. Showering, cooking and plant life also add moisture inside a building. Thermal comfort is affected by evaporation of this moisture and evaporation depends on the relative humidity in the room. Good comfort, where most people are satisfied, is within a narrow range of relative humidity of between 45 and 55 percent. Less satisfactory but acceptable is at most 60%. Below 40% the air starts to become dry and static filled. While standalone humidifiers and dehumidifiers can be bought for each room it is easier, less expensive, and more effective to integrate humidification within the heating cooling and ventilation system. Systems like Unico will automatically adjust 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. If it is not up to the task, the occupants often decrease the set point of the thermostat until comfortable. This is energy wasteful and doesn’t always improve comfort. It can also lead to IAQ problems with mould caused by surface condensation and high humidity.”
Up until now heating has been the biggest consideration for us in the UK, but with increasingly air tight homes, the likelihood of us all spending much more time indoors and record temperatures ventilation and air conditioning are set to play a more central role in all our lives. The free Chartered Institute of Plumbing & Heating engineers and Unico Systems heating, ventilating and cooling CPD can be accessed online via
www.bit.ly/CPDVent
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AIR CONDITIONING, COOLING & VENTILATION
Richard Soper CBE on how heating engineers can benefit from the home improvement boom
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