Energy modeling can help you decide which HVAC system is best
New technologies can be great, but aren't always a great fit
Once upon a time not too long ago, it was simple to pick out an energy-efficient HVAC system for your latest construction project: there were maybe two to choose from.
All that has changed.
"There are a lot of innovative technologies available now for commercial buildings that offer great energy savings," says Tao Jiang, an energy management engineer with BC Hydro. "But it's not good to blindly adopt the latest thing for your new building."
For example, Jiang cites ground source heat pumps and air source variable refrigerant flow systems. Used in Europe and Asia for years, they've recently become popular for new commercial buildings here.
"It's the newest trend and great technology," he says, "but it's not suitable for all projects."
Heat pumps, variant refrigerant flow systems not always ideal
A ground source heat pump will work at its best only if the site's ground conditions are right, and the building itself requires close to equal amounts of heating and cooling throughout the year. If the heat extracted from the ground cannot be compensated for by the waste heat from the building or adjacent ground, the balance will be off and the building will most likely require an additional heating source — reducing or eliminating energy savings.
Likewise for a variant refrigerant flow (VRF) system. It can modulate the output of an outdoor unit and share heat between multiple heating and cooling zones by transferring wasted heat from indoor units in cooling mode to spaces requiring heating. But for it to work at optimum efficiency, zoning must be carefully and accurately planned based on space heating and cooling loads.
How to pick the right system
Jiang and BC Hydro colleague Bojan Andjelkovic, a specialist engineer, recommend energy modeling.
"Modeling programs can run whole-year detailed simulations," says Andjelkovic, "to show how a particular building will perform at different times of day and night and in different climates.
"By doing this at the early concept design stage, you can interactively explore different design strategies — you can see, for example, what happens if you change a building's orientation, shape, mass or envelope, or if you use different building systems and energy sources. It's much more time- and cost-effective than trying to make changes later."
And it definitely works.
Energy modeling helped Sparkling Hill Resort in Vernon, B.C., select its state-of-the-art hybrid ground source heat pump/fan coil system. The result: a 39 per cent reduction in the resort's heating energy consumption and a 14.2 per cent reduction in its cooling energy consumption over a comparable building with a traditional HVAC system.
It also helped the design team behind a new building in Burnaby, B.C., choose an air-source VRF system that saves about 34 per cent electrical energy a year over a conventional HVAC system.
Both buildings went through BC Hydro's New Construction Program, which can cover up to 100 per cent of the cost of having a professional energy modeler complete a simulation. BC Hydro also provides incentives to install energy-conservation measures.
"Energy modeling allows the design team to test out their ideas and demonstrate to their clients why they are recommending one system over another," says Jiang. "And the owners then have the benefit of long-term operational savings on their energy use. Everyone wins."