Our Approach: Energy consumption is a vital concern for us. Therefore, we vigorously engage in a range of energy conservation initiatives. In 100% of our office buildings, for example, we have installed highly efficient lighting fixtures and state-of-the-art lighting controls. In various buildings across our office portfolio we have completed HVAC upgrades and replacements, installed extensive new insulation in walls and roofs, brought on board new smart grid and smart building technologies, utilized reclaimed groundwater in our cooling towers, installed new high-efficiency drives, compressors, pumps, and motors, and developed energy programs to work with our tenants to reduce their energy consumption.
Our primary management methodology is EPA’s Energy Star Portfolio Manager program. This widely acclaimed tool provides a framework for collecting energy data and highlighting opportunities for efficiency improvements. Currently 91% of the total square footage in our office portfolio is included in our Energy Star Portfolio Manager program, and we expect to have 100% of our office buildings actively utilizing it by the end of 2015. This will provide us with a comprehensive reporting platform for our properties and allow key comparative analyses.
Leading The Way in Energy Efficiency: To be eligible for the prestigious “Energy Star” certification, a building needs to achieve a score of at least 75 – meaning it is more energy efficient than 75% of comparable buildings in the US. Our average Energy Star score across the 91% of our office portfolio currently in the program is 76 (and 81 excluding one office building that is heavily occupied by energy-intensive data centers), highlighting that our office buildings are among the most energy efficient in the nation.
Lower CO2 Emissions
We have been able to collect meaningful CO2 emissions data for 96% of the square footage in our office portfolio. In 2014, for that 96%, our average CO2 emissions per 10,000 square feet was 108 metric tons (not including our one major data center property). This is 9% lower than the US average for office buildings of 118.6 metric tons. (1)
- Lighting controls include programmable automated controls, occupancy sensors, time clocks, and photovoltaic sensors.
- High efficiency lighting fixtures contain T-8/T5 fluorescent bulbs with electronic ballast, compact fluorescent, or LED bulbs.
- Energy management systems include programmable automated controls, remote on/off and monitoring and/or control of building systems and equipment.
Reducing Energy Use By Up To 40%
As the fourth tallest Class A office building in Atlanta, One Ninety One Peachtree Tower has become an Atlanta icon with its Acropolis-style structures at the building’s pinnacle. To help improve its energy performance, we have recently completed an air rebalancing initiative based on actual need versus design criteria. Completed in 2014, the effort resulted in the correct amount of outside air being brought into each customer’s floor. Prior to this initiative, outside air was set to the maximum floor occupancy. Our new procedures, including the addition of variable speed drives to the outside and exhaust fans, allow each floor to be controlled to the exact amount of air needed based on each floor’s actual current population – which our analyses found to average 40% less than the “design” parameters.
The 90’s Club
Three of our buildings have earned an Energy Star rating of 90 or above, ranking them among the most highly energy efficient buildings in the nation. Fifth Third Center (with a score of 95) in Charlotte leads the way, joined by 816 Congress (93) in Austin and Terminus 200 (90) in Atlanta.
Persistence Produces Energy Conservation
Located in the heart of Atlanta’s Midtown Arts District, the Promenade Building was originally designed for operating its chiller plant as a 24/7 operation. No longer requiring this operating schedule, our team embarked on several large projects consisting of major HVAC equipment/system replacements, sequence of operation modifications, and multiple energy management upgrades.
The results have been substantial breakthroughs in energy efficiency. For example, we installed new elevator machine room cooling units to replace existing fan coil units. The existing fan coil units required the central plant to be in constant operation. New hybrid units were installed allowing use of chilled water from the central plant during operating hours and shifting to self-generating water source heat pumps to provide cooling when the plant is off-line. With these units replaced, the central plant can be unoccupied, disabling all equipment operation.
Additionally, the central plant sequence of operation was fully modified for a demand based variable flow application, which allows the plant to deliver the necessary tonnage to the building while minimizing excessive pumping and equipment wear, optimizing plant functionality, and increasing energy savings. The outside and exhaust air ventiliation systems for the building were also examined to ensure proper building flows and pressures were being maintained. We installed variable speed drivers on all fans and balanced the outside air and exhaust air risers to current ASHRAE regulations for standard builing tenant occupancy. The outcome: a reduction in required air to be introduced into the building by almost half. This also significantly reduced the fan energy required along with the need for conditioning the outside air brought into the building, resulting in even further energy savings.
B-DOC (Big Data On Command)
Energy management and building automation systems can be complex, especially when managing energy cost, consumption, and carbon footprint data across a large office property portfolio. Cousins has many office properties that are controlled by a number of high quality but quite diverse building automation systems, serviced by many different utility providers. Each of these automation systems speaks their own language. B-DOC is a comprehensive software platform developed to interpret the many different data languages, and provides building output data that allows each building to be compared not only to itself over time, but to its peers and to Energy Star, all in a standard language and format. Beginning in 2015, analytics from this platform will be used to provide answers to some longstanding questions we have been interested in that were hard for us to answer previously due to system differences and the amount of time and cost required to validate and manage the data.
(1) US National Average from US Department of Energy Buildings Energy Data Book.