Energy Load Calculations Vital to Design of Energy-Efficient Apartments, Architect Says
By Caitlin Jones & A. J. Johnson
4 min read
Tax Credit Advisor August, 2006: Developers can substantially cut energy costs in newly built or rehabilitated apartment buildings by insisting on energy load computations to guide the design of plans and specs, according to New York City architect Chris Benedict.
This approach, she noted, results in the design of the most energy-efficient building possible, curtailing energy leaks through the building envelope, preventing the installation of equipment and systems that utilize more energy than is necessary, and a more enjoyable and healthy environment for residents.
With 10 years’ experience in “making housing green,” in both gut rehabilitation and new construction of apartment buildings in New York City, Benedict said her own definition of “green” is “making a building that works very, very well, and works on many different levels.” This process, she added, results in a building “that uses very little energy, is incredibly durable, is going to last a very long time, and is very healthy.”
Systems Approach
Benedict, who spoke on a panel June 15 at the National Leased Housing Association’s annual meeting in Washington, D.C., said she uses a “systems approach” to develop her design for a building. “I look at how the building envelope is constructed, how the heating system is done, how the ventilation system is done, and all the energy use in the building.”
Benedict noted that projected energy usage amounts – energy load calculations – for all elements of the building are essential to achieving the most energy-efficient design for construction or rehabilitation of an apartment building. Under this, she said, calculations are made of all the energy amounts required for the building. “So you look at how much heating, hot water, and electricity is necessary for the basic functions of the building,” she explained.
enedict said energy loads for multifamily housing have been tabulated and understood for years. Nevertheless, she indicated they aren’t being prepared all the time. “So,” she advised, “if you are a developer and you’ve hired an architect and an engineering team, a very savvy thing that you can do is to actually see these calculations.”
She noted energy load calculations are essential because they’re the “basis for design.”
Savings Areas
Benedict said that in her own projects, because of the energy load calculations she does, “I can reduce my boiler size to a quarter of the size” normally used, thereby reducing energy usage and costs. She noted her buildings utilize hot water systems for heating, with room-by-room thermostats in each apartment that – supported by the different construction methods and ventilation systems she employs – reduces overall energy use for the building.
Benedict noted that energy load calculations can also produce savings by fostering designs that call for the installation of equipment or mechanical systems that are of adequate – but not excessive – capacity to perform the required function, thereby avoiding wasted energy and costs. As an example, she cited one building using a powerful domestic water pump to carry water to the top of the 38-unit apartment building, where another piece of equipment was needed to reduce the water pressure before it was piped into the individual apartments for use. “You’ve wasted energy by pumping it up and then reducing it [the pressure] down,” she said. Benedict said this system would costs about $4,500 a year for electricity to run it, while the system she uses costs only $80 per year.
“Every electrical piece of equipment in your building should be looked at,” Benedict said. “If you’re working with someone who’s designing the building – architects and engineers – they should be asked to look at everything that consumes electricity in the building. Because often pumps are oversized, elevator motors are oversized,” she added.
Benedict said lighting is another area where huge energy savings can be realized. She said some buildings, by switching light bulbs to fluorescent, have cut total energy use by 30 percent.
Benedict noted that her designs promotes an efficient interaction between the building envelope, ventilation system, and heating and cooling system, so that energy-efficiency overall is enhanced and less energy used as a result.
No Additional Cost
Benedict said she has taken about 50 gut rehab projects through her “sustainable strategy” approach to design, and currently has two new construction projects underway and two new construction projects online. “In all cases it has not cost more to do this,” to make the buildings more energy-efficient, she said.
Because she works on buildings in the Northeast, where the climate is cooler and therefore more energy is used for heating, Benedict said variations in her approach would be necessary for designing more energy-efficient apartment properties in other regions of the U.S.
