Jason Bennett of indoor climate solutions provider Zehnder Group UK explores why including the consideration of heating and ventilation systems at design stages is the most effective approach, but it’s being overlooked
Traditionally when designing properties, heating and ventilation systems were seen as two very separate entities. Factoring in both, along with other essential building systems, can be problematic for architects, and as a result, this has often led to ventilation being a last-minute thought, or overlooked completely.
However, in our efforts to build tighter for better energy efficiency and to meet our net zero targets by 2050, ventilation has had to shift to the top of the priority list for every build – and yet it’s still not properly considered, or its potential fully realised.
A ventilation – or air distribution – system shouldn’t just be considered in isolation from the other building systems but integrated to work together and fully complement one another. The evolution of these services within a home means that systems can now be more integrated for energy efficiency and futureproofing – and it is time more thought is given around that at the design stage.
Ventilation systems can do more than provide better indoor air quality for occupants inside the dwelling – although that is reason enough for factoring them into building plans. An effective and integrated air distribution system can also assist with the heating and cooling load for the property, and this should be a consideration for any indoor climate strategy.
The initiative towards heat pumps replacing boilers is a key driver in this shift. Heat pumps are now being prioritised to supply heating for the home, but few realise that by using a reversible heat pump, in conjunction with a mechanical ventilation with heat recovery (MVHR) unit and water coil battery, heat output can be greatly increased – and vice versa when cooler temperatures are required.
As human beings, we naturally generate heat within our homes – through cooking, bathing and general living. This heat warms the air inside our homes but quickly becomes stale and needs to be refreshed. With an MVHR ventilation system this stale air is extracted and filtered. But before leaving the house, the air passes over a heat exchanger which recovers the heat that would otherwise be lost outside. MVHR systems provide ventilation with heat recovery of up to 96%.
With an integrated air distribution and reversible heat pump system, this tempered (now filtered) air is passed over the water coil battery containing hot water inside from the heat pump and gains substantially more heat before being supplied into living spaces. These systems have already proven effective across warmer, colder and more humid climes in our European markets.
Then in the summer months when cooler air is required, the MVHR activates its modulating bypass to prioritise the recovery of the cooler air through the system. This provides a comfortable climate all year round as well as clean, fresh, filtered air for better occupant health and wellbeing.
And with a reversible heat pump, cold water supply to the water coil can also substantially cool the tempered air into the property.
Integrated systems for overheating problems
An ability to cool as well as heat is essential for futureproofing homes. Our recent summers have already been characterised by extremes in the UK’s climate. Temperature records soared beyond 40°C for the first time and large parts of the country experienced unprecedented discomfort through overheating.
With this in mind, there will be less of a drive for heating in new builds and an increased focus on cooling. And yet people will still want it. Therefore, it is vital that building designers consider a heating and cooling strategy that works efficiently and seamlessly together.
Within the UK Building Regulations, Approved Document Part O provides guidance to building designers on mitigating overheating in residential buildings; reducing the effects. The prescriptive approach within the Approved Document architects on optimising glazing, solar shading and natural ventilation clearly outlines preferred solutions to keeping a building cool.
But problems occur when external factors dictate that passive ventilation can’t be used to control internal temperatures. In this scenario, a mechanical ventilation system such as MVHR forms the base of the strategy for overheating.
Incorporating an integrated system that cools when required can mitigate overheating from the outset, and this can then be adapted accordingly to ensure compliance with best practice guidance (CIBSE TM59) for residential properties.
Space saving and optimised delivery
When planning an integrated system into a build, it is not only important to get the delivery of heating and cooling set up in the best way but also specify the best installation for the services. Design consideration should be given to aesthetics at this stage – how the room will be used and how occupants will operate in the space.
Traditional methods to heat and ventilate the property don’t always need to be used. Heating and cooling systems can be provided in combination with existing specifications to assist with the delivery of air into the living areas via many different means.
Semi-rigid ducting for example can take 8 kN of weight on top of it, so it can be laid into the screed of the building and won’t affect its performance. This extends the options for ducting installation and allows for supply air to be delivered from below as well as through the wall or ceiling.
Heating and cooling from below can also be done via trench systems – a comprehensive heating solution that is installed into furrows dug beneath the floor, where an insulated steel box casing is discreetly hidden away from view. Generally, this heating system is installed around the perimeter of a room to create a heat curtain across large windows, but can also be adapted to deliver a supply of fresh air into a room via the integrated ventilation system.
Heating and cooling from above should also be a consideration. Floor and wall space is often at a premium, so using radiant heating panels for heating and cooling in the ceiling can free up precious space in the room for furniture. It also makes maintenance and servicing easier and more accessible.
Discreet supply and extract valves can also be installed into the corner of a ceiling to distribute airflow evenly across the ceiling and into a room. Using an innovative airflow pattern known as the Coanda effect, the air dissipates directionally using blanking plates, so no downward draughts are felt, yet clean air is delivered optimally into the room it serves.
Designing for the future
Homes of the future will see systems working together as one, adopting climate strategies for the property that fundamentally change the layout of a building to assist with how we live in it – creating more space, better indoor air quality and cost savings through more energy efficient systems.
Imagine a home that is powered by solar, driving energy into a heat pump that provides heated or cooled water into a ventilation system that also delivers additional heating or cooling by feeding radiators or radiant panels on the ceiling to create whole house climate control – all systems working together like cogs in a machine, unseen and unheard.
Only when we look outside the norm and imagine a different approach to a building ecosystem, will it significantly improve not only the health, but also the wealth, of the homes we design and build.
Jason Bennett is national business development manager at Zehnder Group UK