According to the U.S. Green Building Council, commercial and residential buildings contribute about 39% of the CO2 emissions in the US every year. Other studies have that figure even higher at around 50%, but that is changing as our building codes are updated. Even in older condo buildings, residents and owners can make changes to reduce their energy usage and their impact on the environment. Here are just some of the ways you can update your old condo building to reduce your monthly bills and your impact on Mother Nature.

Solar Energy: Owners can get ahead of the curve and slash your monthly energy bills by installing a solar panel system on your condo roof. For condo boards, this can reduce your monthly costs if hydro is not paid by the individual tenants. The cost of solar systems has dropped drastically in the last decade and the return on investment will be greater with condos than it will be for residential systems as costs are shared by residents.

Roof Gardens: These provide a welcome reprieve from the concrete jungle for both condo owners and animals like birds. Use your roof garden to grow vegetables, herbs, and fruit which provide residents with organic, locally-grown produce.

Permeable Pavers: Reduce water run-off and the chance of flooding and water damage while providing natural drainage that helps to bolster water table levels.

Energy Star Appliances: Using these energy-efficient models in laundry rooms, party rooms and gyms will help to reduce energy bills that are paid by condo boards. Energy-star heating and cooling systems will also reduce costs and the environmental impact of your condo building.

Get an in-home energy usage display through programs like Peaksaver Plus for tenants who pay their own electricity bills. Studies show that when residents can monitor their energy usage, they are more likely to reduce consumption.

Lightbulbs: While replacing lights does require a capital outlay for owners and tenants who pay their own bills, just changing your five most used bulbs will save you $75 a year. Energy-efficient lightbulbs not only use less energy, they also last longer than incandescents. Installing LED fixtures can reduce your lighting bill by up to 50%.

Peak Hours: Post notices in the elevator or lobby which remind residents of peak-hour pricing for energy. Running appliances during the off-peak hours can really help to reduce your monthly bills.

Individual Metering: Heating and cooling accounts for about 49% of condo energy costs. Tenants who have to pay for the heating and cooling of their units tend to use less energy. Encourage the use of smart thermostats which reduce heating and cooling activities when tenants are away at work or sleeping.

Water Heaters: Residents should also reduce water heater temperatures to 115-120°F so large tanks of water aren’t constantly maintained at high temperatures.

Low-flow fixtures: Installing low-flow 6 liter toilets can reduce water usage by 50%. Low-flow shower heads and faucets will also contribute to water savings.