In order to reach the 2050 net zero targets, building designers are faced with some tough choices. Louise McHugh of Vent-Axia explains how heat recovery ventilation can provide the efficiencies plus the right air quality, while avoiding overengineering
Despite the Government slowing down on its route to net zero, the UK still has the legal target to meet net zero by 2050. Rather than putting sustainability on the back burner to meet these targets it is important to make changes now to ensure we meet this goal. Buildings account for 40% of energy use in Europe, and approximately 35% of emissions. To meet the Government’s 2050 net zero target, buildings need to decarbonise, which will involve the wide-scale electrification of heating, a move away from fossil fuels, as well as significant improvements to air tightness and building insulation. Heat recovery ventilation is set for significant growth, as it plays its part in helping to deliver the final piece of carbon emissions reduction in buildings.
To meet the necessary carbon reductions, buildings are becoming more thermally efficient with greater insulation, and their air tightness is increased to avoid heat loss. However, without considering ventilation alongside these measures a building can end up with condensation, mould and poor indoor air quality (IAQ). Energy efficient heat recovery ventilation therefore supplies a solution that provides healthy filtered air while recovering heat that would be otherwise lost.
Energy efficiency
Designers of low carbon and carbon neutral buildings will therefore be pleased to know that the latest commercial heat recovery units, such as Vent-Axia’s Sentinel Apex, have been designed to be highly energy efficient with industry-leading low specific fan powers (SFP) and low embodied carbon; they also ensure occupant comfort is a priority by operating quietly and effectively improving IAQ. Recovering as much as 93% heat recovery efficiency, this type of unit saves huge amounts of energy that would be otherwise wasted; good news for carbon reductions.
To ensure a building operates as designed, it is also vital to ensure it is commissioned correctly. To make commissioning simple, the latest heat recovery units therefore feature advanced control systems that provide on-board, in-room and app-based control, where full functionality commissioning and monitoring is provided as standard, ensuring a unit meets its energy efficiency targets as designed.
Energy wastage
When selecting commercial heat recovery, it is vital to choose a unit where every element has been considered to avoid energy wastage. Heat recovery featuring demand control optimises IAQ while minimising ventilation energy consumption, only ventilating when required. Demand ventilation also helps with compliance with Approved Document F which states occupied rooms in commercial buildings must have means of monitoring IAQ. CO2 demand-controlled ventilation can ensure good IAQ, as per Part F.
However, specifiers should be aware when selecting a heat recovery unit that there are some elements that can hamper efficiency. Filters are an important element of a unit – to maximise good IAQ, high level filtration is vital. But filters need to be chosen wisely, since a poor choice might affect the heat recovery unit’s efficiency resulting in a higher SFP.
Another feature to consider when specifying commercial heat recovery is summer bypass. As buildings become increasingly airtight the threat of buildings overheating is growing. As well as IAQ and energy efficiency, thermal comfort is vital for building users. However, a summer bypass is another element that can negatively affect performance. Specifiers should consider an integral automatic summer bypass designed to provide free cooling when available, but ensure that it is sized to eliminate performance loss.
Sizing in general is an important factor when it comes to heat recovery – over specification of a unit wastes energy. Specifiers should choose a heat recovery unit which meets the necessary airflow requirements. There are free cloud-based tools available that allow specifiers to select fans to exact duty points so the fan will operate in a building as designed.
Embodied energy
As energy efficiency reaches greater heights, there is greater focus on the embodied energy of products in our buildings. To reduce embodied, energy specifiers should look for products that are UK-manufactured, with the supply chain involved as short as possible. Also opting for a product that is completely serviceable and maintainable so each component can be removed and replaced if necessary, is very helpful in extending the life of a heat recovery unit. It is also important to consider the end of life of a product ensuring it can be easily re-purposed or recycled.
When designing a building to be low carbon or carbon neutral, there are many challenges to consider, from selecting materials to co-ordinating multiple layers of supply chain management. Obtaining accurate and up-to-date embodied carbon information is crucial for ensuring that the building meets its carbon reduction targets. However, this can be a time-consuming and complex process, as it requires data to be collected from multiple sources, including suppliers, manufacturers and contractors.
Manufacturers are therefore now taking additional steps to provide the embodied carbon information that designers need such as by using CIBSE TM65 data collection methodology to collect accurate and detailed embodied carbon information. Working from a component level, this methodology ensures that data are comprehensive, and up-to-date.
So, when building designers are considering how to ventilate a low carbon or carbon neutral building, heat recovery ventilation is a good solution. By focusing on energy efficiency, avoiding energy wastage and considering and measuring embodied energy, designers can successfully reduce carbon in buildings as we head towards net zero 2050.
Louise McHugh is product manager at Vent-Axia