8 minute read
HVAC
Comfortable, safe, and sustainable air
WORDS MATT MCDONALD
While choosing HVAC systems has always been about keeping people comfortable, increasingly it’s also about ensuring the air they breathe is pure; and that the systems that deliver them this fresh air are sustainable.
If there’s one thing that COVID-19 has taught specifiers, it’s that when considering HVAC requirements, they must remember the ‘V’ in that acronym is for ‘Ventilation’. As we’ve come to learn over the two-plus years of the pandemic, ventilation – along with social distancing, mask wearing and so forth – has an important role to play in controlling the spread of the virus (and many others).
Beyond that, of course, ventilation is irreplaceable in terms of maintaining Indoor Air Quality (IAQ). It ensures that a building’s occupants remain not only comfortable, but unaffected by the negative ramifications of being without fresh air for long periods. Turning to the other HVAC elements, ‘Heating’ and ‘Air Conditioning’, the good news is that the market continues to present new ways for specifiers to reduce their reliance on traditional temperature control methods, and in so doing, play their part in reducing carbon emissions.
For these reasons, instead of actual heating and cooling systems, the following selection of HVAC products for commercial applications focuses on products that can be used alongside such systems to regulate their use and improve their efficiency; as well as a couple of the best recently released ventilation products.
AWS
In the past, poorly sealed facade construction, and the consequent leakage of air in and out of buildings, had the unintended positive consequence of maintaining IAQ. It allowed fresh air into buildings. Conversely, the current emphasis on airtightness and protecting the building envelope – intended to improve thermal efficiency and reduce energy costs – can negatively impact IAQ.
While the move to thermal efficiency is welcome, it does not negate the need for ventilation. After all, poor IAQ and a lack of fresh air have their own negative consequences on not just the comfort of a building’s occupants, but their health. For example, in office settings poor IAQ has been shown to contribute to sick building syndrome, a phenomenon that can cause respiratory illness, increase absenteeism, reduce employee comfort, and result in productivity losses.
Addressing this issue, AWS Trickle Vent is an integrated trickle ventilation system that enables natural ventilation of otherwise well-sealed modern buildings, without the need to open windows or doors.
An unobtrusive solution integrated into the supplier’s range of windows and doors (both residential and commercial), AWS Trickle Vent uses a patented shape memory alloy spring system to automatically adjust a ventilation inlet, in line with changes to ambient temperature. It requires no motorisation, electricity, sensors, or human intervention and ensures no drafts or major changes in temperature as a result of its operation.
Because it operates continually in the background, regardless of whether or not a space is occupied, it is an ideal solution for a range of commercial, educational, healthcare applications, and the like. AWS Trickle Vent is available in six models to suit different applications and window types. Utilised as part of a larger HVAC system, it can allow controlled infiltration when ambient temperatures are available, and effectively offset heating and cooling demands.
Importantly, AWS Trickle Vent also incorporates a range of features to improve its effective operation and safety. These include an air filter that is able to reduce up to 68% of typical airborne dust; an insect, rodent and ember screen, which has a maximum aperture of just 2mm; an intumescent fire barrier; and a manual override.
In terms of sound absorption, the AWS Trickle Vent can be specified with an optional proprietary ‘Soundout’ absorber. This includes sound wafers that trap and absorb sound but have no effect on airflow. RENSON
Performing a similar task to the AWS Trickle Vent, though taking a different approach, is Renson Waves, the first fully automated, decentralised ventilation unit with moisture, Volatile Organic Compounds (VOC) and carbon dioxide CO2 measuring capabilities.
Suitable for a range of commercial applications, including offices and schools, the product only activates according to actual ventilation requirements. Using intelligent sensors, it is able to detect when IAQ is such that operation is required. In this way, unnecessary operation of the system is eliminated, and energy consumption is minimised.
The key notion behind the introduction of Renson Waves is that, unlike temperature, the key indicators of IAQ (Moisture, VOCs, and CO2) are undetectable by the human senses. At the same time, if not controlled, each is potentially harmful.
Excessive humidity can cause mould, a problem that once it appears can be hard to remove and has negative health consequence. Meanwhile, VOCs – as found in numerous building products, as well as in some paints, nail polish removers, fuels, cleaning products, and more – can in the most extreme cases result
in serious respiratory illnesses and cancer; and, though harmless in small amounts, excessive amounts of CO2 can also have detrimental health effects.
Unless any of these variables are present and the unit’s sensors are triggered, the unit will simply operate at the minimum level required for healthy IAQ. Then, once excessive moisture, CO2, or VOCs are detected, it springs into action to remove it.
Unlike other systems that detect, say movement, Renson Waves works regardless of whether there are people in a room or not. So, for example, if an employee enters the bathroom to retrieve his/her misplaced glasses, it will not unnecessarily activate. That won’t happen until the sensors deliver the relevant readings. In this way, it is able to reduce energy usage by 30 – 50 percent, as compared to ventilation systems that are not demand-controlled.
With Renson Waves retrofitting is an option. It is compatible with all existing ventilation ducts with a diameter of 100mm or 125mm. It also features an energy-efficient fan that includes a fine damper blade and therefore experiences only minimal pressure loss. Easy to install, its design is unobtrusive and suitable for simple integration into most fit-outs and designs.
ABOVE AWS Trickle Vent is an integrated trickle ventilation system that enables natural ventilation of otherwise well-sealed modern buildings, without the need to open windows or doors.
EBSA
EBSA is a commercial louvre supplier, specialising in technologies that combine natural light and ventilation with automated window systems, in order to help create buildings that are not only comfortable places in which to work, but also energy efficient and sustainable.
Though not a supplier of actual airconditioning or ventilation systems, EBSA offers solutions designed to interface with these HVAC systems, and in so doing, to create hybrid solutions that are practical, effective and efficient.
EBSA interfaces with HVAC systems to provide what is termed a mixed mode strategy. The result is to maximise the use of natural ventilation when conditions are suitable, and then call for heating or cooling systems to kick in when external conditions become unfavourable for natural ventilation. An example of such a project is the Parramatta Council and Library building currently being undertaken by Built. Though it features an HVAC system, it also incorporates thermal chimneys to promote effective natural ventilation in conjunction with EBSA double glazed louvres and natural ventilation controls.
As mentioned, the COVID-19 pandemic has focussed attention on the fact that aerosols are responsible for airborne transmission of the virus. As such, there is plenty of attention currently being given to integrating systems such as EBSA’s, which monitor CO2 levels and can automatically modulate windows or louvres, with the aim of purging stale air.
EBSA systems are able to distinguish between a user opening a window manually for fresh air (in which case, the mechanical heating or cooling system is shut down) and the windows opening in response to the presence of high CO2 levels in the room. In the latter case, it may not be desirable to shut down the HVAC in the short period the purging is active.
MISTAFOG
There are times when climatic conditions are out of the ordinary; hot summer days when ambient temperatures move beyond the ideal operating range of air conditioning systems and their effective operation becomes problematic. This is particularly true in the case of systems that employ air-cooled condenser units for their cooling capacity. They need to expel heat in order to re-compress their coolant and continue normal operation.
One of the best ways to address this problem is by using an evaporative air conditioner misting system, like the Mistafog Coilcool. By ensuring continued operation, it is able to not only reduce energy and maintenance costs, but also increase the peak cooling capacity of systems.
The experience of the Australian Botanic Garden, at Mount Annan in Sydney’s southwest, illustrates the effectiveness of the Mistafog Coilcool. The facility has two large condenser units to cool both its public spaces and research facilities, which house many millions of seeds, including those belonging to 60 percent of the threatened species in NSW.
During the summer of 2017/18, after excessive heat saw the air-conditioning system experience multiple failures, the Garden called on the assistance of Mistafog with the instructions that they needed a way to ensure the air-conditioning always remained fully operational to preserve their seed collections.
The system that Mistafog installed is operated automatically via the building management system. This monitors conditions within the building (including the air conditioning systems) and activates the misting system whenever pre-cooling is required.
Following installation, tests to measure it effectiveness showed that, with the precooling activated, there was an immediate drop in power consumption of 6.82 percent. Combined with efficiency improvements that made it possible to run fewer compressors than before installation, energy savings on the day of testing were in excess of 30 percent.
