High-rise implements heat pumps and outdoor air systems for decarbonization
660 Fifth Avenue, developed by Brookfield Properties, highlights how a building redevelopment can be leveraged by property owners to improve functionality and efficiency of building systems, setting a successful precedent for high-rise offices of the future. The 41-story, 1.4 million square foot commercial property was built in 1957 and is currently completing a full redevelopment to modernize the building.
The decarbonization plan for 660 Fifth Avenue involves a phased approach from 2023-2035 to electrify heating and eliminate steam usage through measures such as expanding the building’s thermal network, installing water-to-water and air-to-water heat pumps, and fine tuning HVAC sequences, with the goal of reducing site EUI by 59.8% and greenhouse gas emissions by over 6,500 metric tons annually.
Brookfield Properties is a fully integrated, global real estate services company that owns and operates 40 million square feet of office, residential, hotel, and retail property in New York.

Project Status
Planning
Under Construction
Monitoring & Evaluation
Project Highlights
Step 1
Step 1: Examine Current Conditions
A baseline assessment is key to understanding current systems and performance, then identifying conditions, requirements or events that will trigger a decarbonization effort. The assessment looks across technical systems, asset strategy and sectoral factors.
Building System Conditions
- System Failure
- Equipment nearing end-of-life
- Damage from events
- Tenant load change
- Comfort improvements
- Indoor air quality improvements
- Facade maintenance
- Efficiency improvements
Asset Conditions
- Repositioning
- Recapitalization
- Capital event cycles
- Tenant turnover/vacancy
- Carbon emissions limits
- Tenant sustainability demands
- Investor sustainability demands
- Building codes
- Owner sustainability goals
Market Conditions
- Technology improves
- Market demand changes
- Policy changes
- Utility prices change
Step 2
Step 2: Design Resource Efficient Solutions
Effective engineering integrates measures for reducing energy load, recovering wasted heat, and moving towards partial or full electrification. This increases operational efficiencies, optimizes energy peaks, and avoids oversized heating systems, thus alleviating space constraints and minimizing the cost of retrofits to decarbonize the building over time.
Existing Conditions
This diagram illustrates the building prior to the initiation of Strategic Decarbonization planning by the owners and their teams.
Click through the measures under “Building After” to understand the components of the building’s energy transition.
Sequence of Measures
2022
2023
2024
2026
Building System Affected
- heating
- cooling
- ventilation












Step 3
Step 3: Build the Business Case
Making a business case for strategic decarbonization requires thinking beyond a traditional energy audit approach or simple payback analysis. It assesses business-as-usual costs and risks against the costs and added value of phased decarbonization investments in the long-term.
Strategic Decarbonization Action Plan
An emissions decarbonization roadmap helps building owners visualize their future emissions reductions by outlining the CO2 reductions from selected energy conservation measures. This roadmap is designed with a phased approach, considering a 20- or 30-year timeline, and incorporates the evolving benefits of grid decarbonization, ensuring a comprehensive view of long-term environmental impact.
