A healthy approach to smart buildings
The availability of ‘smart’ indoor climate systems is allowing building services designers to match conditions more closely to the comfort and health requirements of occupants, according to Swegon.
Buildings are responsible for around 40% of global energy consumption with HVAC systems being the biggest contributor. A range of factors including climate, location, insulation levels etc. determine energy usage, but the availability of digital technologies means building services designers are gaining more control over how a building will perform in use.
Digitalisation and connectivity are crucial changes that allow designers to match the performance of indoor climate systems to meet user demand. The availability of wireless networks means systems can be more easily configured, commissioned and controlled. It also gives engineers a route to tackling the individual pieces of equipment that consume the most energy, such as fans and chillers.
It also gives design engineers the tools with which to unlock the full potential of demand-controlled ventilation (DCV), which can reduce the amount of fan energy used by as much as 80%. The overall energy saving for cooling and heating can be up to 40% compared with constant air volume (CAV) systems. This is because air, cooling and heating are supplied in just the right amounts, at the right places and at the right time based on the real time user demands.
This also has important implications for the health, wellbeing and comfort of occupants. Most buildings regularly operate at occupancies below the design maximum. In these cases, demand control and monitoring of indoor climate indicators can reduce the ventilation, heating and cooling loads while improving indoor air quality (IAQ).
Using intelligent networks allows the building operator to manage a predictive maintenance programme so that systems are under surveillance 24/7 and any maintenance requirements can be addressed before performance starts to dip. In many cases, software updates can be transmitted directly to individual pieces of equipment to ensure they continue to operate as intended or adapt to new tasks if the usage of the building or occupied area changes.
The design approach that led to the development of variable air volume (VAV) systems was refined to produce the modern DCV systems that not only control temperature (and humidity), but also optimise the supply air volumes – particularly outdoor air – to improve the indoor environment while also minimising energy costs.
Swegon’s WISE DCV system is an example of how this cutting-edge technology is being applied in UK buildings.
It uses a self-healing mesh network that ensures a wireless system cannot be undermined by any interruption or strength reduction in the signal it uses to communicate between different products installed throughout the building. As a result, the wireless installation is commissioned without communication cabling, which reduces time, cost and complexity while also making it very simple to operate and change in the future.
The use of distributed sensors and motorised air volume control dampers with linked optimising controllers can create a system that constantly adjusts itself in response to the presence – or lack – of occupants. Studies have shown that, in cellular offices, typically fewer than 50% of rooms in an office block are occupied concurrently and the ‘normal’ peak may only ever reach about 80% of all offices.
With a CAV system the airflow rate is kept constant, while with a DCV system it is modulated to meet the actual usage of an area. It can also be configured to respond to manage the level of carbon dioxide (CO2), volatile organic compound (VOC) or other elements that can have a detrimental effect on the health and well-being of occupants.
Products, such as dampers and diffusers, communicate via integrated radio nodes. This means significant cost savings thanks to reduced cabling and it eliminates the risk of misconnections.
The base products on the WISE network are interconnected through a hardwired IP network, but the majority of the system – the products distributed throughout the building to provide heating, cooling and ventilation in separate zones and rooms – are linked by the wireless radio network.
As well as a general lack of hard wiring throughout the network, the batteries that provide power to the individual sensors in each piece of equipment have an operating life of 10 years.
The wireless technology allows for ease of commissioning and simple reconfiguration of the system when changes are made to room layouts or usage patterns.
Being able to deploy the very latest in wireless technology underpinning a robust and reliable communication network opens up all sorts of possibilities for building services systems. The WISE network is already in use in over 100 projects worldwide – including a project in Stockholm that achieved a BREEAM ‘outstanding’ rating. This technology is now appearing in UK buildings.
DCV systems, in general, have the potential to provide a significant reduction in energy usage when compared with systems with a constant airflow rate, while also achieving good levels of occupant comfort. However, to realise this potential requires close collaboration throughout the construction process and supply chain, so Swegon uses its dedicated local presence to provide installation, commissioning and maintenance support for the life safety, cooling and ventilation systems it supplies.
“One of the biggest challenges facing the industry is improving integration,” says Swegon UK&I Indoor Climate Director Dene Kent. “The complexity of controlling HVAC systems is one of the more difficult aspects of a project along with space available on site. However, these challenges can often be overcome if good control logic and optimum system sizing based on demand-controlled ventilation are used – and if teams collaborate from an early stage in the design process.”
For more information visit: wise.swegon.com