For a few months now, we’ve been chronicling our efforts to ‘green’ the office with the goal of achieving net-zero energy consumption. One of our first big items was the switch to LED lights, since lighting accounts for 30% of total energy use in the typical office building. Now it was time to look at the cost of staying comfortable.
In most workplaces, heating and cooling systems comprise over a third of the total energy draw — 25% and 9%, respectively. Our office already had a ductless heat pump installed when the practice moved in. To check out its efficiency relative to other systems, we spoke with our downstairs neighbour, Kristen Pronick of Axis Heating & Cooling. Kristin helpfully provided a comparison of various heating systems (figures based on a 2,000 square foot premises built after 1990).
Many offices have electric baseboard heat, which offers 100% efficiency and costs approximately $1989 per year. We learned that a ductless heat pump like ours has 250% efficiency, and costs about $796 annually – a 60% savings over electric baseboard heat. With an area of about 640 square feet, our small office has averaged about $22 per month in hydro costs; this is right in line with the figures that Kristen provided. As an added benefit, our heat pump serves double-duty as a cooling system when afternoon temperatures soar in the summer. The only system that’s better rated is a geothermal heat pump with 450% efficiency, but it does come at a higher initial cost that makes it less feasible for our premises.
To find out the actual carbon cost of using hydro, we consulted Mike Berners-Lee’s excellent book, “How Bad Are Bananas? The Carbon Footprint of Everything”. According to this source, spending one dollar on hydro costs 4 kg of CO2e. Compare this to spending a dollar on solar panels, which SAVES 2 kg of CO2e. Spending that dollar on rainforest preservation saves an even more impressive 220 kg. We’ll talk about the carbon credit economy another time; for now, here are some other energy-related tips: Week 4 carbon footprint table