ENERGY EFFICIENCY MEASURES

Lighting

Description of Approach
To take full advantage of the daylighting features in the AAAS building, such as light-shelves and the architectural notches, NRDC installed clerestory windows in the interior walls of the window offices. These 2½ foot tall indoor windows, located above eye level, allow sunlight from the office windows, as well as electric lighting, to penetrate into the corridors and the interior office space. Because of these clerestory windows, natural light can be seen from nearly everywhere in the office.

Along with the extensive use of daylight, NRDC used a task/ambient lighting strategy to minimize the amount of electric lighting required in the office. Most offices are excessively lit to uniform levels, but our approach is to provide differential lighting levels throughout the space. NRDC uses lower lighting levels throughout much of the office to save energy, while providing bright light where it is needed most -- on the work surface. To implement the task/ambient lighting design strategy, NRDC combined many existing innovative lighting technologies, including T-8 tri-phosphor and compact fluorescent lamps, electronic ballasts, occupancy sensors, and high efficiency direct/indirect pendant fixtures.

Environmental Benefit
NRDC's efficient lighting system will reduce air pollution and the emission of greenhouse gases by eliminating the need for additional electricity generation. We estimate that every year, our new office lighting alone will prevent the emission of 132,000 pounds (66 tons) of carbon dioxide (CO₂), 1,500 pounds of sulfur dioxide (SO₂) and 470 pounds of nitrogen oxides (NO_x).^[18]

Performance and Cost
NRDC's office has a calculated connected lighting load (peak demand) of 0.53 Watts per square foot; standard lighting power density in commercial office space is 2.0 Watts per square foot or more. NRDC's lighting electricity consumption is approximately 1.9 kilowatt-hours (kWh) per square foot per year, compared with 7.5 kWh/sq.ft. in a conventional office, representing savings of almost 75%. NRDC's total lighting savings run about 115,000 kWh per year. Though we spent an extra $33,000 for our lighting system, NRDC's efficient design will save about $12,000 a year in energy costs for a 2.75-year simple payback.

Other Considerations
NRDC uses fluorescent light sources exclusively in its space. These lights contain traces of mercury, a heavy metal that can contaminate ground water if it leaches out of a landfill. However, this amount of mercury is trivial compared to the amount of heavy metals emissions from power plants avoided because of higher efficiency. Lighting manufacturers are working to reduce mercury content in fluorescent lamps, but have not yet succeeded in eliminating it.

Where to Get It
A list of the fixtures NRDC used in its office can be found in Appendix 1. In general, these fixtures should be available from most quality lighting equipment distributors in your area. Information about local distributors can be obtained from the manufacturer.

Appliances and Office Equipment

Introduction

NRDC also installed energy efficient and environmentally friendly office equipment and appliances, including the widespread use of Energy Star computers, monitors, and printers, and energy conserving refrigerators and dishwashers.

Product Description
The Energy Star^[19] computers that NRDC uses are designed to save about 40% compared to conventional machines. Eighty-five percent of our machines (computers, monitors and printers) are Energy Star compliant.^[20]

In the fourth floor kitchen, the NRDC showcases the "Golden Carrot" or Super-Efficient refrigerator, which was designed to exceed the Department of Energy's most stringent standards by at least 25%, while eliminating the use of CFCs in the refrigerant and insulating foam. The "Golden Carrot" refrigerator is the result of the Super Efficient Refrigerator Program (SERP), an NRDC initiative that brought together a utility consortium to create a cash incentive for the company who designed the most efficient refrigerator that did not use CFCs. Whirlpool won the contest, making them eligible for the $30 million pool of funds that was raised by the program. Receiving these funds, however, is contingent on selling the refrigerator, with a certain rebate available for each machine sold.

A second refrigerator, manufactured by Sun Frost, is located upstairs in the fifth floor kitchen. The Sun Frost refrigerator is designed with the compressors and condensers located on top of the freezer compartment, rather than below the refrigerator compartment as on most refrigerators, so that they cool efficiently without having the heat they generate re-enter the cabinet. A normal refrigerator wastes over 30 percent of its energy removing excess heat from the compressors and condensers, while the design of the Sun Frost prevents this heat from reaching the food compartment in the first place. The walls are highly insulated (with very tight seals around the doors), and the refrigerator operates without air circulation fans, further reducing energy consumption. In each kitchen, NRDC also installed very water and energy efficient Bosch dishwashers.

Environmental Benefit
Compared to an office using conventional appliances and non-Energy Star computers, annual energy savings for the appliances and equipment is about 26,000 kWh, resulting in reductions of 40,800 pounds of CO₂, 460 pounds of SO₂, and 150 pounds of NO_x.

Performance and Cost
The Whirlpool SERP refrigerator uses only 640 kWh, compared to about 850 kWh for a standard model in its class and uses HCFCs for the refrigerant and insulating foam blowing agent. A SERP refrigerator costs approximately $900, which is actually less than other top-of-the-line models that have lower efficiency.

The Sun Frost unit is the most energy efficient refrigerator made in the country, using only 240 kWh, about 1/4 as much electricity as a standard refrigerator. The Sun Frost runs about $1,000 (about a third of this is shipping) more than a comparably-sized conventional refrigerator and has fewer bells and whistles.

The Bosch dishwashers, which are extremely quiet, consume about 570 kWh (assuming electrically-heated hot water) compared with 760 for an average unit, about 25% less energy. Different models cost between $700 and $900.

NRDC's total computing energy use is an estimated 9,600 kilowatt-hours compared with about 13,900 kWh (30% savings), if none of our machines were Energy Star compliant.^[20] Similarly, NRDC is saving about 20,500 kWh per year with Energy Star printers, compared with conventional printers.

Other Considerations
Since it can also run on DC power, perhaps the most cost-effective application for a Sun Frost refrigerator is in a home that uses photovoltaic panels, since the avoided capital cost of the panels is far greater than the extra cost of the refrigerator.

Where to Get It
You can get information about Energy Star computers and printers by calling the EPA at (888) 782-7937. Call the SERP program for information about the Super-Efficient Refrigerator at (800) 306-0994, or call your local electric utility company to see whether they participated in the program. Sun Frost can be contacted at (707) 822-9095 and the Robert Bosch Corp. at (800) 944-2904.

Heating and Air Conditioning

Introduction

NRDC was not involved in the specification of the building's air conditioning system, which was done by the Croxton Collaborative, which specified most of the energy and environmental features of the AAAS building. However, the gas-fired absorption system that AAAS chose is the system the Croxton Collaborative would have installed when they designed our New York office if an appropriately-sized unit had been available at that time. Generally, an occupant in an office building has little control over the choice of HVAC (heating, ventilation & air conditioning) system, unless they're the owner.

Description of Features
The AAAS building, uses an innovative gas-fired absorption air conditioning/heating system with two 250 ton chiller/heaters made by the Trane Corporation.^[21] The absorption process uses water as the refrigerant, rather than CFCs or HCFCs and that relies on upon lithium bromide^[22] as a heat transfer fluid. A 60 ton electrical centrifugal chiller that uses an HFC^[23] refrigerant is run during periods of low cooling loads.

To increase the system's efficiency, variable speed ventilation fans are used to closely match the supply of air conditioning or heating and ventilation with the demand. The system also reduces fan-use energy by supplying low volume, low speed, heated or highly chilled air. Since ventilation energy use is related to the cube of the air speed, small reductions in air speed result in large decreases in energy use. Special variable air volume boxes in the ceiling then thoroughly mix the conditioned air with the re-circulated office air. The computer controlled ventilation system also provides additional outside air circulation, pumping 25% more fresh air into the offices than an ordinary system.

Personal climate control units are installed in all perimeter offices to give people control over their own environment. Efficient variable-speed pumps supply these units with either hot or cold water depending upon the season, and each has a thermostat and a fan that can be controlled by the occupant.

Environmental Benefit
When designing the AAAS building air conditioning, the engineers strove to produce a system that allowed individual climate control and met stringent environmental criteria. The first priority was to avoid the use of CFC or HCFC refrigerants in the primary air conditioning system, which is accomplished by the gas absorption system. While an international treaty ends the production of ozone depleting CFCs by the end of this year, HCFCs, the replacement chemical that will be used in conventional refrigeration systems for the next several years, are also damaging to the ozone layer.

The AAAS HVAC system is estimated to save 47% compared to the energy use of a system that simply complies with the building code. Although AAAS evaluated a system that used slightly less source energy than the one they used, the more efficient alternative had slightly higher pollution emissions due to the nature of the fuel mix of power generation in the PEPCO service territory.

AAAS's engineers estimate that this system reduces CO₂ emissions by 2.8 million pounds, SO₂ emissions by over 2,000 pounds, and NO_x pollution by over 4,000 pounds each year.

Performance and Cost
Compared with efficient electric centrifugal chillers, absorption chiller/heaters cost more per ton of cooling capacity, but they eliminate the need for a boiler so the extra cost is minimal. An energy rebate for the gas equipment further reduced the cost of the gas system to equal or below that of an electric unit. Although electric chillers tend to have a higher coefficient of performance (COP),^[24] annual fuel costs for gas units are much lower: $178,000 for the AAAS system, compared with $323,000 for a conventional one. More efficient variable speed fans and pumps were used, but their prevalence has led to almost no cost differential compared with standard equipment. In addition, the low temperature/low-volume system is less noisy and requires smaller ducts, saving on ceiling height and materials cost.

Other Considerations
The conditioned air in NRDC's office is introduced to the space using specially-designed Valid Air diffusers by Warren Technology which increase thermal comfort by releasing the air parallel to the ceiling, preventing the formation of "pools" or "cascades" of cold air and stagnant air pockets.

Where to Get It
Valid Air diffusers are available through Warren Technology at (800) 231-1084. You can call the Trane Co. for more information about their gas absorption chiller/heater at (301) 984-2400. Randy Croxton or Kirsten Childs of the Croxton Collaborative can be reached at (212) 794-2285.

Building Envelope

Description of Features
Transom windows and light shelves in the perimeter offices work and architectural notches cut into the building's facade were designed to take advantage of daylight to illuminate the interior spaces. Daylight, in combination with NRDC's high efficiency lighting system helps reduce our electric lighting requirements by 75% compared to a conventional office and making our space brighter, healthier and more productive.

In addition, these windows play another important energy-conserving role in reducing air conditioning and heating needs. Filled with argon, an inert heavy gas, and coated with a low-emissivity film, these double-glazed windows are designed to keep out unwanted heat from sun during the summer, while reflecting space heat back into the office during winter. Finally, each window can opened (only 3 inches so that the balance of the air conditioning system is not disrupted), providing additional fresh air and comfort for the occupants.

To further reduce energy consumption, the building installed 3.5 inches of fiberglass batts in the walls to achieve R-11 in the whole wall, including the windows, which are about R-4.5 (equivalent to 5 panes of glass). Four inches of rigid Styrofoam board were used in the roof for an R-21 insulating value.

Environmental Benefit
The insulation, windows and daylighting features all contribute to the pollution reductions discussed under the lighting and heating and air conditioning systems, since they reduce the total energy service needs that must be met.

Performance and Cost
High-performance windows, generally characterized by having low-e coatings and being filled with inert gases, come at a 5% to 25% premium compared with conventional double-glazed windows. However, this extra cost is quickly paid back by reduced heating and air conditioning bills and can also lead to lower capital costs through downsizing the air conditioning system.

Where to Get It
AAAS's windows use Viracon glass in CFM aluminum frames that were fabricated by Harmon Contract Glazing in Maryland. Call: (410) 536-5115 or (410) 247-1788.

Elevators

State of the art elevators employ a "fuzzy logic" system that records usage patterns for each floor during the day and pre-programs elevators to be ready to serve anticipated passenger loads based on historical patterns. This system reduces waiting time up to 30% and reduces energy use through optimizing the location of elevator cars to serve passengers.

Notes

18. See the Appliances and Office Equipment section for other energy savings and environmental benefit estimates.

19. Energy Star is a program run by the U.S. EPA that sets voluntary energy reduction targets for electric equipment and systems and certifies those models that comply with the energy performance levels.

20. Energy Star products feature hard-drive and monitor shut-down technologies that were pioneered for portable computers to prolong battery life. These features put computers, monitors and printers into a low-energy "sleep" mode that reduces energy consumption between 50% and 80% when the machine is not in use for a prolonged period.

21. According to the energy calculations for the building, this system appears to be oversized by about 100 tons, but in order to potentially accommodate a less efficient tenant in the future, the larger capacity system was installed.

22. Lithium bromide is a salt solution that is not considered hazardous, though you wouldn't necessarily want to drink it. The substance is not covered by environmental regulations requiring special handling or disposal.

23. As distinct from HCFCs, HFCs are non ozone-depleting because they do not contain chlorine.

24. COP is the net refrigerating effect divided by the heat equivalent of mechanical work. Generally, the COP of an electric chiller will range between 3 and 5, while that of an absorption chiller ranges between 0.8 and 1.2.