7 Ways to Retrofit Buildings for Energy Efficiency
Retrofitting represents one of the best opportunities to improve the environment in our cities. Two-thirds of the buildings that exist today will still be standing in 2050, and since buildings account for as much as 70% of a city’s carbon emissions, the opportunity to retrofit existing real estate is vast.

Upgrade the Lighting
Upgrade the light fittings from fluorescent tubes and halogen bulbs to more efficient, longer-lasting LEDs.
- cost
- $
- payback
- 2–4 years
Upgrade the HVAC
Replacing the pumps, fans and motors will make a building’s heating, ventilation and air conditioning (HVAC) equipment more efficient.
- cost
- $–$$
- payback
- 3–6 years
Optimize Performance
Lighting, heating, ventilation in a commercial building account for 60-75% of its primary energy use. Adjust existing lighting and air conditioning settings according to a building’s occupancy rate to reduce energy use.
- cost
- FREE
- payback
- Immediate

Empire State Building
Retrofitting in Action
The retrofit of New York's Empire State Building has made it one of the world’s most energy efficient buildings.
Through a combination of eight energy efficiency projects—including retrofitting of all the 6,514 windows, reusing 96% of the original frames and glassware, plus the installation of 67 elevators that generate electricity instead of heat when braking—the building has already reduced its energy consumption by more than 40%, with annual energy savings of $4.4 million. In April 2019, New York City Council passed legislation, known as Local Law 97, to mandate all existing buildings 25,000 square feet or larger to reduce their greenhouse gas emissions by 40% by 2030 and by 80% by 2050.
- Location
- New York, U.S.
- Year Built
- 1931
Implement a Waste Strategy
Separate recyclable materials and paper from waste. Ban single use plastics. Compost food waste or dehydrate and incinerate it to be recycled as fuel.
- cost
- $–$$
- payback
- 4–5 years
Use Continuous Commissioning
Circular economy strategies could eliminate the equivalent of 9.3 billion tonnes of CO2 by 2050. Invest in sensors and real time, every day data tracking to look for anomalies and opportunities to reduce waste and increase efficiency.
- cost
- $–$$
- payback
- 4–5 years
Organize “Treasure Hunts”
Use cross-functional teams of employees, clients and supporting vendors to create a social network to identify productivity, efficiency and waste reduction opportunities.
- cost
- FREE
- payback
- Immediate

ZIN
Retrofitting in Action
The plan to retrofit the existing World Trade Centre (WTC) in Brussels will make it the most energy efficient building in the Belgian capital.
Converting the WTCs towers will create ZIN, a highly-efficient, mixed-use development with offices, co-working space, apartments, a hotel, a 1,500-square meter roof garden, plus leisure, restaurant and shopping facilities. This project reimagines a workspace with 24/7 occupancy and has been designed with circular economy principles in mind. During its construction, almost 95% of all the materials and existing equipment will be recovered, reused or recycled, with 65% of the existing buildings maintained, limiting the need for new construction materials. About 30,000 tonnes of concrete from the demolition will be reused on site, another 1,000 tonnes of products and materials, including wood paneling, carpets and insulation, will be reused on site or in other locations.
- Location
- Brussels, Belgium
- Year Built
- 1972 (Tower I)
1976 (Tower II)
Elevator Controls
Use elevator lockouts to balance the number of people in buildings versus the elevators available at key times. The ability to manage building access and occupancy during a pandemic will help control exposure and spread.
- cost
- $–$$
- payback
- 4–6 years

One Post Office Square
Retrofitting in Action
The redevelopment of One Post Office Square serves as a model for a holistic retrofit, signifying the transformation of Boston’s Downtown.
Designed for value, experience and performance, JLL, Gensler and Anchor Line Partners worked with the building owner to transform an outdated office tower into a sustainable building of the future on par with new construction. It’s also uniquely positioned to deliver on post-Covid expectations for office buildings. Replacing the concrete facade with triple-glazing, installing an intelligent heating and cooling system and LED lighting will improve its energy performance by 20%. The reuse of materials will realize a saving of 14,500 metric tons of embodied carbon. Health and wellness, including better ventilation, access to daylight and fresh air (twice the code minimum requirement), and on-site amenities will be priorities. Scheduled for completion in fall 2022, One Post Office Square is targeting LEED V4 Gold certification.
- Location
- Boston, U.S.
- Year Built
- 1981






