GREEN MATTERS AC after Covid O
n February 22nd 2021 The Prime Minister Boris Johnson released a four-point plan explaining how the UK will gradually lift itself
out of lockdown, writes Jason Tinsley of Pacair. For many people the key dates were, when are the kids going back to school, when are the pubs open and when are we going to get back to normal. The date for normality we have been given is 21st June, all being well, for when things go back to normal. This will be the date when it is hoped all legal limits on social distancing can be removed. We can then pack up our temporary work stations located in spare rooms, lofts, dining tables, kitchen sides and broom cupboards and all go back to the office and enjoy the social company and interaction many have missed over the last year. For many businesses though the pandemic may have given them the opportunity to address how they use their offices and even in some cases whether they need an office, however for the majority, it will be business as usual at some point this summer. The 21st June will be a date that all facilities managers and building owners have in the diaries. The date for peeling off all those 2m gap stickers and yellow and black floor tape and one way arrows, give the office a good dusting and welcoming people back. So now would be a good time to look at the HVAC equipment in the building with regards to air quality and system efficiency as one thing that pandemic has taught us is the importance of fresh air ventilation to prevent the spread of Covid19. Back in October last year CIBSE published their
Ventilation Guide version 4. This document was updated to provide guidance on how to reduce the potential for airborne transmission of Covid. It focuses on the importance of providing fresh air. The underlying principle is to dilute and remove airborne pathogens as much as possible, exhausting them to the outside and reducing the chance that they can become deposited on surfaces or inhaled by room users. The guide also covers various ways of providing fresh air including mechanical heat recovery as a method of both supplying fresh air and extracting stale air at the same time whilst recovering heat energy normally wasted to outside. The guide also covers different methods of UVC light disinfection technologies available to help disinfect airborne Covid particles. The pandemic has given air conditioning manufacturers the opportunity to develop systems that can reduce the risk of contracting Covid19 in air
32 June 2021
conditioned spaces. Some have built the technology into their fan coil units or supply optional parts to inhibit or neutralise the Covid19 particles on new or existing systems. These methods tend to use either some form of electrical field or ultra violet (UVC) light to inhibit or neutralise viruses once they get captured or pass through the return air stream to the air conditioning unit. Whilst it’s difficult to judge the real world effectiveness of these systems outside the laboratory over the coming months these devices and technologies will enter the market and will be of interest to some building owners, consultants and specifiers of HVAC equipment as it may take some time till the risk of infection disappears. Whilst the offices are at relatively low occupancy it makes sense to use the opportunity to give existing HVAC systems a service as it will help to improve both air quality, comfort and operational cost. Unknown to many building managers the initial investment in new HVAC equipment represents only 5%–10% of its lifecycle cost. Over time, the cost of operation— particularly what you’ll spend on energy—might add up to 10 to 20 times more than what you originally spent for the equipment. Regular six monthly cleaning and serving,
depending on environment, can make a significant difference to an air conditioning system and end users. Clean filters, coils, fan blades, check and clean drain pans and drain pumps etc can all help towards increasing a systems efficiency and or reduce running costs. In a recent report from
Energy.gov stated that replacing a dirty clogged filter with a clean one can lower an air conditioner's energy consumption by 5% to 15%. Even the best HVAC systems won’t deliver ideal performance without proper maintenance. Dirt and dust acts as an insulator, keeping the heat trapped inside and reducing the heat exchange transfer. The system will need to run longer and harder to do its job. The temperature coming out of a dirty outdoor condenser coil will also be higher lowering the cooling capacity. The results of all these issues are increased running costs, equipment breakdown along with reduced lifespan of the equipment. Even a fine layer of dust and dirt on a condenser coil can cause up to a 20% drop in efficiency and can increase energy usage by up to 35%. The air conditioning and refrigeration industries have been provided with a number of targets and incentives to limit their environmental impact through improved energy efficiency (indirect emissions of carbon dioxide) and reduced refrigerant leakage (direct emissions of greenhouse gases). Electronics have continued to assist in increasing
energy efficiency; inverter control is now provided to most fan motors and compressors; seasonal efficiency can be increased by optimising evaporating and condensing pressures based on the load. Running costs have been greatly reduced; the equipment is considerably lighter and quieter. In 2006, F-Gas regulations were introduced with the target of reducing refrigerant emissions. For the first time, a legal obligation was placed on equipment operators to maintain records of the quantity and type of refrigerants used to ensure that the systems were checked for leakage. Refrigeration technicians were required to be qualified and to maintain records of leakage checks and refrigerant used. The F-Gas regulations have since been updated; the weight of the refrigerant is now factored by its global warming potential (GWP) when calculating both the frequency of leakage checks and more significantly, the quantity of HFC refrigerants that can be placed on the EU market. By 2030, this will be reduced to 20% of the quantity sold in 2015. At 2088, R410A’s GWP is relatively high and disproportionately affected by this regulation. The first significant reduction in its availability occurred in 2018 and resulted in that significant price increase. The F-Gas regulations have also determined that from 2025, R410A won’t be used in new, small single split systems. The introduction of a new mildly flammable safety group (A2L), has allowed R32 (GWP 675) to be reconsidered; many manufacturers have already adopted R32 in their split systems. The resulting performance is more efficiency and refrigerant charges are reduced by up to 20%. However, increased consideration to the consequences of leakage must be given on larger systems. The lockdown has also provided an opportunity to gauge the effects of less human activity. Pollution levels (particularly nitrous oxide) have already fallen dramatically; many have noted that blossom has been particularly spectacular this year and that birdsong has replaced the constant background of motorway and aeroplane noise. Scientists have also measured a 6.4% reduction
in global emissions during the pandemic which has helped to trigger some governments around the world to either join or recommit to the Paris Climate Agreement. The US has recently committed to a 50% cut in carbon emissions by 2030 compared to 2005 levels and U.K Government announced that they are now on target to cut carbon emission by 78% of 1990 levels by 2035 (with the help of decarbonising heat with heat pumps) 15 years ahead of original target set for 2050.
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