With COP26 behind us, the words ‘Net Zero’ still hangs heavy in the air as we look to make the most of the momentum gained by the summit. On the face of it, it’s a daunting task. However, like so many challenges in life, it becomes considerably more manageable when broken down into smaller steps.
It’s now a widely accepted fact that lighting, heating, and cooling operating emissions account for a significant proportion (28%) of all carbon emissions emitted by building and construction (which is 39%). Given this, HVAC seems a good focus area to make good progress in the race to decarbonize.
Making a shift to reduce carbon footprint
Fortunately, the HVAC industry also benefits from technology capable of supporting ambitious green strategies. Pureplay mechanical ventilation systems, while popular, are undeniably carbon-intensive. By shifting to smart, automated natural, or hybrid natural and mechanical, systems, building managers and business owners can take a significant step towards reducing their carbon footprint.
As such, I’d like to take this opportunity to look at what a green HVAC strategy, incorporating intelligent natural ventilation, might look like and how it can help businesses achieve that all-important Net Zero ahead of 2050.
Sustainable use
Using the right system allows for minimal disruption through quiet background automation Modern passive ventilation systems comprise so much more than simply opening windows, having evolved to incorporate smart sensors, which monitor and adjust for variables inside and out.
Technology exists which enables your windows and BMS to communicate with one another, helping to optimize setpoints to achieve the best performance while complementing the energy use of other building systems. Further, using the right system allows for minimal disruption through quiet background automation, quick reaction to changing conditions, and improved security.
Smart systems
However, it’s not the technology alone that optimizes energy efficiency, but also the way it enables the building to interact with the outdoors. When appropriately designed and controlled, passive ventilation systems harness the potential of natural elements, such as wind and thermal buoyancy, to regulate temperature and improve indoor air quality (IAQ) by bringing fresh air in and sending stale air out.
Put simply, smart passive ventilation reduces reliance on carbon-intensive mechanical ventilation systems, consequently lowering a building’s operational emissions. This means less maintenance and significantly lower utility bills. In some cases where a hybrid approach, combining natural and mechanical ventilation, is more appropriate, the benefits remain unchanged.
Sum of the parts
Smart-controlled passive ventilation can enhance material-based thermal performance
Passive ventilation is one piece of a much larger green construction puzzle. As effective as these systems are, their impact can be amplified when considered in tandem with other modern, eco-friendly design and building techniques, such as low-energy lighting and material-based approaches including ‘fabric first'.
Smart-controlled passive ventilation can enhance material-based thermal performance, working with a structure’s thermal mass for efficient and effective cooling throughout the day.
Going further, organizations can consider eco-friendly power sources for their HVAC, passive or otherwise. For example, the latest PV solar panels are reliable energy generators, potentially producing enough clean energy to power smart-controlled ventilation systems and deliver a comfortable interior with freely circulating, high-quality air.
Fundamental foundations
To implement an effective passive ventilation system, there are a few key things to be aware of. The first of these is ensuring a good understanding of how it works and the design and operational processes behind it. Whether manual or automatic, the type and location of the window most appropriate for a setting depend on the building itself, its spaces, usage, and occupants.
The physical layout of your building presents a different range of potential approaches: typically single-sided or cross ventilation for smaller buildings, with the addition of stack ventilation using stair cores, light wells, and centralized atria across multiple zones for larger buildings.
Ventilation strategies
Next, you’ll want to consider good control strategies to optimize performance and deliver levels of comfort, air quality, and energy efficiency virtually unachievable with only manual operation.
There are three essential ventilation strategies to consider:
- Night cooling: In summer, using cooler nighttime air to ventilate the building securely, reducing peak building temperatures the next day.
- Purge ventilation: Timely opening of windows before occupants arrive to freshen up spaces without the risk of discomfort.
- Preemptive ventilation: Reacting to changing room conditions and carefully beginning to ventilate spaces before room conditions begin to fail, considering weather conditions to keep rooms as near to ideal setpoints as possible.
Intuitive and cost-effective delivery
Well-proven smart options are available which significantly improve functionality and performance Even a great design supported by a well-thought-out strategy can fall flat without supporting technology. This last piece of the puzzle will ensure the quiet, intuitive, and cost-effective delivery of your natural ventilation.
Don’t stumble on this last hurdle by using low-tech components, which could create barriers to good performance and add cost to infrastructure. Well-proven smart options are available which significantly improve functionality and performance and often prove value-add and cost-neutral.
A balance between ventilation supply and demand
A system comprising less capable actuators is likely to function at a fixed speed and often operate noisily. Basic systems may only react once room conditions have failed, opening windows more aggressively and bringing in undesirable amounts of outdoor air in an attempt to recover the space. This can cause unstable and uncomfortable conditions as well as reduce actuator life.
The best solution is aiming to achieve the ideal balance between ventilation supply and demand, opening periodically in smaller increments to adjust and hit the right balance of air quality, comfort, and energy, for as much time as possible.
BMS can tell the windows to open to specific percentage positions quietly for minimizing any disruption
An identical design, using the right technology, enable your windows and BMS to communicate with one another. In this situation, the BMS can tell the windows to open to specific percentage positions quietly for background automation, minimizing any disruption, and reacting more quickly if it starts raining or to an override function.
Hero to zero
As the UK sets its sights on Net Zero 2050, focusing on energy-efficient new buildings isn’t enough to pass the finish line. Design and construction need to consider the UK’s ample existing building stock, frequently performing poorly and contributing significantly to operating emissions.
Fortunately, recent projects demonstrate energy efficiency and retrofit needn’t be mutually exclusive. Along with providing the opportunity to contribute to a healthier environment, refurbs focused on reducing emissions also set the foundations for happier building occupants. Equipped with a good understanding of the sustainable benefits and fundamentals of natural ventilation, you can now breathe a little easier as you approach your next project.
