The App Challenge project that Michele discusses below can be viewed from her team’s profile on the ECCE GitHub website:

This year I participated in the ECCE App Challenge for the third time. My team included Matthew Brown, lead designer, Tasos Dardas, lead developer, and myself, lead researcher.  Our App, Sustainera, is a web application that estimates the potential energy and CO2 savings of buildings and neighborhoods in Toronto, Ontario.

In Canada, buildings account for almost a third of annual greenhouse gas (GHG) emissions. As Canadian cities continue to grow, so does the demand for energy. Buildings have a substantial impact on the environment as they use resources, generate waste and are costly to maintain and operate. Our app aims to promote sustainable buildings using 2 strategies: reducing energy/water consumption and planting green rooftops. Choosing efficient insulation, lighting and appliances saves energy, lowers utility bills, increases indoor comfort and reduces impacts on the environment. Green roofs act as a rainwater buffer, reduce noise and air pollution, regulate indoor temperatures by providing extra insulation and absorb CO2, making urban areas less likely to become heat islands.

As the lead researcher, my role was to determine the potential energy savings from LED light bulbs, spray foam insulation and choosing efficient toilets, washing machines and dryers.

LED Light Bulbs 

LED light bulbs are significantly more efficient than incandescent light bulbs as they use less energy and last longer.

The savings from replacing incandescent light bulbs with LED light bulbs are based from the values above, also assuming 5000 lumens are required for every 250 square feet and each bulb produces 800 lumens (LED and incandescent). To convert the area from square meters to square feet, the area of the building is multiplied by 10.7639.

Savings ($) = (((((Area of Building in m2*10.7639)/250)*5000)/800)/25)*3966.73


Spray foam insulation can reduce energy consumption by being more efficient in preventing heated air (in winter) and cooled air (in summer) from escaping homes. In Toronto, spray foam insulation ranges from $1.75 to $3.00 per square foot with an average professional installation cost of $2021. The calculation used assumes a cost of $2.00 per square foot and a spay depth of 1 inch. Based on previous case studies, spray foam insulation reduced a household’s monthly energy bill by an average of 48%. Therefore, in this calculation, we will assume installing spray foam insulation will reduce the monthly energy bill of the user by 40%.

ROI (years) = (building square foot*2+2021)/((Cost of Monthly Energy Bill*0.4)*12)


Most older, standard toilets have an average flush volume ranging from 6 to 13 litres while high efficiency toilets have an average of 4.8 litres. The ROI for replacing existing toilets with high efficiency ones is based on the assumption that each person flushes the toilet 5 times a day, the cost of a high efficiency toilet is $120 and a standard toilet flushes at a volume of 9 litres. Effective April 1, 2019, the rate of water consumption in Toronto is $0.004747688/litre, which is used to calculate ROI.

ROI (years) = (# of Toilets to Upgrade*120)/((# of People*5*9)-(# of People*5*4.8)*0.004747688*365)


The average household of 4 people washes roughly 400 loads of laundry each year, which roughly equates to 2 loads a week per person. The ROI uses the estimate of saving $0.21 per load and a difference of $250 between a standard and high efficient washing machine.

ROI (years) = 250/(# of people*2*52*0.21)


Union Gas estimates a savings of $91.00 a year from switching to a natural gas dryer versus an electric dryer. This comparison is based on a household of 4 people, so the ROI assumes a savings of $22.75 per person annually. It also assumes a gas dryer is $100 more than an electric dryer.

ROI (years) = 100/((# people in household/4)*91)

With new constructions, renovations or retrofits, buildings in Toronto can achieve superior levels of energy efficiency by using fewer resources, reducing waste, improving air quality and eliminating negative environmental impacts. Buildings that are chosen to be more sustainable will face higher initial costs, but the difference will be easily recovered over time through energy savings. Not only do green buildings benefit tenants and households with savings in utilities, but they also lower maintenance costs and increase property value for building developers. Hopefully our app has raised some awareness in the benefits of choosing efficient lighting, insulation and appliances and helped people make more sustainable choices!