Window retrofit increases energy efficiency, occupant comfort, and savings.
Located on The Green in New Haven, CT, 195 Church is undergoing a $6-million energy-efficient window and lighting retrofit. Implementing recommendations from Globelé Energy, New Haven (globeleenergy.com) and Apogee Enterprises Inc.’s Building Retrofit Strategy Team, Minneapolis (apog.com), the property’s tenants already are experiencing more comfortable workspaces. The local building owners, 195 Church Street Associates LLC, are also noticing significant annual energy savings. The building is on track to earn an estimated $589,000 rebate from utility provider United Illuminating (UI), New Haven (energizect.com) through the EnergizeCT initiative.
“There has not been a capital improvement of this magnitude to a building in New Haven in many years,” observed Christopher Vigilante, chief operating officer of Northside Development Co., the property-management company for 195 Church where the business also is a tenant. Currently, the 244,000-sq.-ft., 18-story, Class A office building is 75% occupied with 28 tenants and 340 occupants.
Improving on History
Built in 1974 and largely constructed of concrete, the building reflects the materials and style of the era. The original windows remain functional, but were manufactured at a time before low-e insulated glass and improved thermal breaks in the aluminum framing were available.
In addition to the aging windows, the property’s all-electric baseboard heating and variable-air-volume system with electric reheat contributed to large utility bills. Seeking to improve the building’s energy efficiency, Northside management worked with the Globelé Energy team to review the property according to the U.S. Department of Energy’s (Washington, energy.gov) benchmarking program and by performing a Level 1 ASHRAE energy audit.
As a regional electric distribution company, UI provides energy-efficiency programs through the EnergizeCT initiative. The initiative is designed to advance the efficient use of energy, reduce air pollution and negative environmental impacts, and promote economic development and energy security.
“UI’s energy engineer, Gary Pattavina, was instrumental in guiding us through the plan and offered very helpful advice and guidance through a very intricate process,” said Vigilante. “The goal was to make this building as efficient as possible thus doing the right thing for the environment and also producing a very good return on our investment.”
Pattavina noted, “Electrically heated buildings are a great candidate for energy-efficiency measures and these types of projects are exactly what we look for at UI. We recognize new energy-efficient windows are a costly investment and the incentives available to our customers help bring that up-front cost down significantly. We were very excited to work with the customer and their design team to help them achieve the energy savings on this window replacement project.”
Modeled for Savings
To achieve the owner’s energy-reduction goals, Globelé facilitators outlined a multi-phased plan. Phase I recommended replacing the old fluorescent lights with new LEDs and updating the 43-yr.-old windows. Helping Northside’s team select the optimal window system, the Apogee team provided an annual energy-savings forecast showing the potential savings offered with Wausau, WI-based Wausau Window and Wall Systems’ (wausauwindow.com) 1297 series S.E.A.L. interior accessory windows. Interior accessory windows are installed from the building’s interior over the existing windows, which were sealed closed to prevent air infiltration. For 195 Church, the S.E.A.L. units feature Viracon’s (Owatonna, MN, viracon.com) RoomSide low-e glass and aluminum framing members finished by Linetec (Wausau, WI, linetec.com) in Dark Bronze anodize.
Using the eQUEST energy-modeling physics-based software tool to simulate the performance of a building on an annual basis, the Apogee team forecasted the level of energy savings that could be achieved by adding an interior accessory window with low-e glass to the existing glazing. From this data, performance predictions were provided on annual energy, peak demand, and daylight energy use.
“Today’s energy-efficient windows can dramatically lower the heating and cooling costs associated with windows, while increasing occupant comfort,” said Apogee Building Retrofit Strategy Team’s certified energy manager, Mike Sheppy. “Optimizing natural light also can contribute to a building’s energy efficiency and tenants’ well being.”
Daylighting and Comfort
The RoomSide low-e glass also improved light-to-solar gain (LSG) ratio by 21%. Sheppy explained, “This improved LSG ratio increases the number of hours in the year that natural daylighting can be used without tenants having to draw their blinds. In addition, electrical lighting can be dimmed or turned off with daylighting controls.”
He continued, “Furthermore, according to the World Green Building Council, natural daylighting can save up to $2,000 per employee in office costs by increasing occupant comfort, leading to higher productivity. Adding an interior accessory window with low-e glass to the existing glazing significantly improves occupant comfort because surface temperatures are much closer to room temperature.”
In Connecticut’s cold months, Sheppy said, “The new glazing will keep the occupants seated in the perimeter spaces of this building more comfortable by significantly reduced radiant heat transfer. These improvements will allow occupants to sit closer to the windows, increasing the usable floor space of the building.”
Comparing the window bays before and after the retrofit, thermal imaging shows window surface-temperature differences of nearly 20-deg. F. Sheppy described, “The new windows stand out in sharp contrast against the old windows. This indicates that the new windows are keeping out the cold 34 F outside conditions, while keeping in the warm 72 F inside conditions.”
As the lead auditor for the building, Globelé Energy’s Alfred Peterson pointed out that the project’s “success is measured by sustainable reduction in energy for a single Energy Opportunity or as a Comprehensive Initiative of two or more projects as was bundled for 195 Church.”
Based on this measure of analysis, the new S.E.A.L. units, in combination with the new LEDs, are anticipated to save 29% in annual electrical consumption. Estimates show a yearly electrical energy savings of $0.95/sq. ft., reducing the owner’s roughly $805,000 annual electric bill by $203,000.