How to add life to a building - while subtracting from energy costs
Binaya KarkiView bio
Back when energy efficiency first became a major trend, there was a lot of talk about the ‘low hanging fruit’ of lighting upgrades. Like magic, swapping the energy-guzzling incandescent globes and fluorescent luminaires for halogens or LEDs would slash energy costs and gain a certain amount of sustainability street cred.
But to improve the performance of a whole building, we don’t start with lighting. The engineering pathway for asset retrofit actually starts with something most people won’t see – stakeholder opinions.
Before we even think about building services, we ask questions to find out what the client, building owner and occupier drivers are. What does ‘better’ look like for the people who have a stake in the building? What would comfort look and feel like?
Where to start with decarbonisation
The biggest battle for many building owners is around decarbonisation, because it isn’t easy to eliminate carbon emissions in existing buildings. Many are connected to gas for hot water and the heating/cooling system, and the majority of the Australian national grid is not renewably-powered yet. Also, many existing buildings are taller than they are wide, so it’s very difficult to install enough solar PV to supply all building and occupant needs (because as the old saying goes, buildings don’t use energy – the people in them do).
The needs and drivers of the stakeholders will ultimately decide if an upgrade, including a mechanical plant and energy upgrade, is going to happen.
But if there is a drive for improving the asset, the best place to start is insulation. Improving insulation is something that will drive energy savings through reducing the need for mechanical heating and cooling. Many buildings will have insulation that is not matching current building code standards. But instead of only upgrading to the current code, it is even better to upgrade beyond that so the building will meet future performance standards.
Think ahead to tomorrow's standards
We know the National Construction Code will continue to make energy-efficiency and passive performance standards more rigorous the closer we get to the Paris target, so it is logical to think ahead to the building’s future in a net zero world and upgrade to that standard now.
Air tightness testing is a valuable process when designing for an insulation upgrade too, as so many buildings in Australia have been poorly finished in terms of sealing the building envelope. Frequent workmanship quality fails include windows with gaps in the fenestration assembly, improperly finished soffits, unsealed penetrations for pipework and doors that let the wind whistle through between the door and the frame.
Air leakage into or out of a building adds to energy consumption - this is why it’s another area where the National Construction Code is introducing more rigorous standards.
When a house is draughty in winter, people turn up the heat; when the cooling is on in summer, and if cool air is leaking out, the air conditioning needs to work harder to keep people comfortable. The same phenomenon holds true across every type of building, big or small, where people quite rightly expect to feel comfortable indoors.
So, if a refurbishment is going to upgrade insulation, identifying and fixing gaps and leaks is a worthwhile part of the job scope as it can bring a building into alignment with passive house standards of air tightness, and therefore reduce energy consumption.
If as part of a retrofit or refurbishment parts of the building structure or fitouts are being renewed, low carbon materials are obviously a good idea. This might mean engineered timbers, or flooring, roofing or structural steel with high proportions of recycled content are good options to consider. Think circular economy and minimising lifecycle impacts as a primary specification for any material.
Apply some smarts
As part of upgrading building services, a smart control system should be designed, which will help automate some significant energy savings functions such as zoning control and occupancy sensors for air conditioning, daylight-responsive sensors for smart lighting and energy monitoring platforms that alert the facilities manager if there is an unusual spike in energy use.
Thermostats can have programmable sensors that enable the system to respond in real-time to actual conditions, as opposed to conventional set-and-forget points. Every time the conditions are within comfort bands without air conditioning, energy has been saved.
Another engineering intervention is to examine the passive solar properties of the building and improve them with strategic shading on heat-exposed elevations or new windows in northerly aspects. Where shading is being installed, it might be worth considering building-integrated photovoltaics (BiPV) for canopies or where there is outdoor carparking, a solar carpark installation.
Improving natural light into floorplates (without bringing in summer heat gain) is a sustainability win, and beneficial for human wellbeing. It is also beneficial to increase natural ventilation, and this can be done in a highly effective way through using Building Information Modelling (BIM) of the structure and spaces, combined with computational fluid dynamics (CFD) modelling of airflow, so we can design for the optimal air movement and air pathways in a retrofit or refurbishment design.
All of these things in combination will lower the energy load on the building, which then means we can right-size solutions for removing any gas-fired plant with electric alternatives. A four-pipe heat pump can replace a gas boiler for both domestic hot water and hot water for the heating system while simultaneously providing cooling. Using the BIM model developed for supporting the passive performance measures, we can establish the best location for the new plant.
Thanks to BIM modelling and BMS systems, the asset owners and building operators also have the benefit of a type of operational digital twin, which will make maintenance more efficient. Basically, the wins and the savings keep multiplying!