Page E1.2 . 18 February 2004                     
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    Architectural Global Warming

    continued

    Conservatory Conservation

    One example of the firm's work, now under construction, is the all-glass Amarillo Botanic Garden Conservatory. The architects manipulated the glazing on each side of the building to create internal conditions to replicate a tropical environment. From previous experience, they've learned the importance of the spectrum of light on plant growth, especially flowering plants.

    Mazria explains: "We are replicating a foreign environment in the building. Amarillo has a cold and hot dry climate, and the exhibit is a hot, humid, tropical environment... Humidity, lighting levels and light wavelengths must be just right. This is a very challenging problem. With a conservatory, you are trying to do many things at once trying to reduce energy consumption and manipulate wavelengths by using the insulating and transmission properties of glass."

    There are many types of glazings on the market with low emissivity (low-e) coated surfaces. Mazria's firm uses "DOE 2," sophisticated simulation software that allows them to manipulate the properties of glazing until they arrive at glass types that are compatible with the environment they are trying to create.

    For the conservatory design, different types of glazing were selected for each side of the building. Mazria cites a slope of double glass in the conservatory that is made up of both low-e and clear glazing. This combination lets in ultraviolet and infrared wavelengths that promote plant flowering, while the low-e coating provides insulation.

    Modeling the Indoor Environment

    The conservatory design offered other difficult challenges to the goal of minimizing energy use. The tropical environment required fogging to add humidity, and lots of air movement and ventilation to prevent mold from forming on the underside of leaves. When plants are watered, they turn the water into vapor through their leaf structure.

    These ventilation and humidity factors must be modeled in the simulation software, as must the sun's daily movement, cloud cover, changing outdoor temperatures, and the conservatory's backup system for heating, cooling, and humidity control. If the conservatory is correctly designed, the mechanical systems are usually quite small, using little imported energy.

    Using DOE 2, architects can compare predicted building conditions with the tropical temperature profiles necessary for plant growth, then make adjustments to the building design glazing properties, building form, and materials until there's a good match. Mazria believes that design work accounts for 80 percent of the reduction in energy consumption in the conservatory, while he attributes the other 20 percent to the mechanical/ electrical systems.

    "In typical conservatories, mechanical/ electrical systems are huge," Mazria explains, "because they are overcoming heat loss and gain through all that glass. The amount of energy you have to put into the facility is large because of the poor insulating properties of glass and high energy requirements for heating, humidity control, and cooling a building of this type."

    In order to be energy efficient, he adds, you must take advantage of the insulating and transmission properties of different types of glass, especially where large glass surfaces are required for transmitting natural light for healthy plant growth.

    Low-Energy Schools

    Mazria's firm has also designed several multiuse structures and schools. The Bosque School in Albuquerque focuses on environmental education and interactive learning. The school buildings are located along the edge of a "bosque," a wooded area along the Rio Grande river, and incorporate water harvesting strategies, wetlands, and indoor and outdoor classrooms. Exterior materials and colors were chosen to blend the campus into the surrounding environment.

    A design requirement was that it should consume about half the energy of an average school in the area. Again, the architects used simulation programs to model energy performance as they were designing so they could make adjustments to get closer to that energy use goal.

    The school is almost completely daylit. "Studies show children do better in daylit spaces, and... because elementary schools are mostly day-use facilities, almost no lights are on in the school," Mazria explains. "Electric light is a premium energy source. There are losses in generating and transmitting electricity of about 60-70 percent."

    Daylighting also saves energy because it reduces the cooling load. South-facing windows and clerestories that are shaded to reduce summer solar heat gain let in ample, glare-free, evenly distributed, diffuse light.

    In addition, the campus was designed as a series of small buildings that form a plaza, paths, outdoor classrooms, and courtyards, which house outdoor meetings and other school functions. In schools, there is also a large requirement for fresh air. To save energy in the winter, another school designed by MRO, Albuquerque's E-School, uses a heat exchanger to heat the cold incoming air with the otherwise wasted heat from the outgoing air.

    Mazria has a "no excuses" attitude about architectural environmental reform. "If you want to achieve something in design," he states, "there are so many ways to do it." The "50-percent energy reduction" design goal is usually achievable at no extra cost by manipulating building form, openings, and materials.

    Discuss this article in the Architecture Forum...

    Susan Smith is the editor of AECCafe, an online news portal for the architecture, engineering, and construction industry, as well as GISCafe and GISWeekly, an online portal and weekly magazine for the geographic information systems industry. She has been writing about architecture and technology for over ten years and resides in Santa Fe, New Mexico.

     

    AW

    ArchWeek Image

    Building operations account for over 3/4 of all U.S. electricity consumption.
    Image: Mazria, Riskin Odems, Inc. (data source: Energy Information Administration, US DOE)

    ArchWeek Image

    The Amarillo Botanic Garden Conservatory.
    Image: Mazria, Riskin Odems, Inc.

    ArchWeek Image

    South facade of the Bosque School in Albuquerque, New Mexico.
    Photo: Mazria, Riskin Odems, Inc.

    ArchWeek Image

    West facade of the Bosque School.
    Photo: Mazria, Riskin Odems, Inc.

     

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