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Active Façade for Lab Buildings: Quantifying Energy and Qualitative Benefits

Syed Faruq Ahmed, P. Richard Rittelmann, and Jayesh X. Hariyani, Burt Hill Kosar Rittelmann Associates

The façade in a lab building is an extremely important design element, not only for energy and building functionality, but also for the building aesthetics. Most lab buildings have used either opaque façade with windows or large glass areas. Both approaches have their own special considerations.

The use of "active façade" opens new opportunities for the lab designs where large glass areas can be utilized in a controlled manner. This results in not only the energy saving but also in enhancing the quality of the lab space near the façade. Active facades have been successfully used in many European buildings. This approach has been applied to a lab building located in the Finger Lakes region of New York State. The laboratory building is located on a site between three buildings such that the only significant façade is the west side. Therefore, the aesthetics of the building dictates the use of high quality façade. The west side presents unique challenges for the sun control, glare control and aesthetics (when the users are allowed to control the shades in their own spaces).

The building utilizes an "active façade" where the lab wall consists of a double glass assembly with Low-E coated argon filled glass. Outside this window is a 2.5 feet wide cavity which is covered with single glass. The cavity contains a movable shading device which allows controlled amount of light into the lab. A small part of the incident solar energy (referred to as Solar Admittance) is allowed to enter the lab, another part is reflected out of the cavity from the shading devices, and some part gets absorbed in the cavity where it is removed as heat by natural ventilation of the cavity. This approach provides a means for controlling the west sun, the heat gain, the glare, and also presents a uniform building view from the outside. The shades are configured to move together so that the building face looks uniform everywhere. On cloudy days the shades can be opened to allow more light in the labs.

In order to quantify the usefulness of the active façade for this application, a large number of studies were conducted on a "shoe-box" model of the lab modules. This allowed the various parameters and arrangement of the glass in the façade to be studied in a manner relative to a base strategy. After the initial screening of strategies, the most beneficial strategy is selected.

An approach for the evaluation of active façade strategies for a lab building has been developed. Several strategies are defined. As an example, the following seven strategies were defined for the building that has been studied:

CASE 1: Low-E double glass on the lab window, no cavity wall (on the outside), translucent shade inside the lab.

CASE 2: Low-E double glass on the lab window, no cavity wall (on the outside), specular reflective shade inside the lab.

CASE 3: Low-E double glass on the lab window, no cavity wall (on the outside), specular reflective shade outside the lab window.

CASE 4: Cavity wall on the outside, Low-E double glass on the outside of the cavity, single glass on the lab window, shading device in the cavity.

CASE 5: Cavity wall on the outside, single glass on the outside of the cavity, Low-E double glass on the lab window, shading device in the cavity.

CASE 6: Cavity wall on the outside, single glass on the outside of the cavity, regular double glass on the lab window, shading device in the cavity.

CASE 7: Low-E double glass on the lab wall, no cavity, no shades – REFERENCE CASE.

The shading device is the active element and can be adjusted automatically to allow a certain amount of solar energy in the space. The active façade provides continuous control of the solar input into the laboratory.

The seven cases for the "shoe-box" building, consisting of two lab modules totaling 968 sqare feet were studied by using TRNSYS hour-by-hour simulation. The results of the simulation show that with respect to the base case (CASE 7) and 30 percent solar admittance in the labs, the heating and cooling energy is reduced by 16.1 percent for CASE 1 to 25.1 percent for CASE 5. All other cases are in between. While the strategy in CASE 5 saves 25 percent of the energy with respect to the base case (CASE 7), using the energy costs for this project, the yearly savings translate to $1,101. Based on a 15-year life and 5 percent discount rate, the maximum allowable incremental cost comes out to be $11,433. This cost is based on energy savings only.

In addition to the energy savings, there are quantitative benefits of using the lab area next to the window more effectively. This amount, conservatively, translates to $22,000 benefit in building cost. Added to this benefit are the personnel productivity improvements which amount to $2.96 per sqaure feet per year, resulting in the 15-year discounted savings of $29,552 for the "shoe-box" model. The total of all the savings discussed above is $63,169 in 15 years which translates to $64.80 per square feet of the shoe-box module. The active façade cost must not exceed this cost which is achievable.

The presentation will provide the details about the building project where active façade is used. The results of the simulations for the whole building using DOE-2.1E will be presented. The details for the estimation of the qualitative benefits will be presented. Also presented will be the performance of the active façade on the south, west, and east side of the lab buildings in several climate types in the United States.

The information from the presentation will provide valuable insight for the building design professionals to use "active façade" as an innovative strategy which not only saves energy but also provides high quality lab spaces where personnel productivity can be maximized.

Labs21 Connection:

The active façade system being discussed in the submission fits into several strategies of Labs21 Approach. The unique and noteworthy aspect of the submission is that the use of "active façade" allows the space to be "higher quality" where users have more control over the environments and, at the same time, saving energy. For the lab buildings, providing high quality space, saving energy, and at the same time maintaining the space functionality, is extremely important.

The Life Cycle Cost Decision Making strategy of Labs21 approach is used to design high quality building façades. Often decisions are based on initial cost only. When operating costs for the building are considered for 15 to 25 years, the "annual cost of operating the building" is minimized. Thus, the initial cost and operating costs need to be taken together. The use of the active façade is one example where the value derived from energy savings and the conservation savings from the qualitative benefit are used to provide high quality space.

Employ a Broad Range of Sustainable Energy and Water Efficiency Strategies Daylighting is known to be one of the most cost effective strategies for building design. Many studies done by organizations such as Lawrence Berkeley Labs have made that determination. The use of "Active Façade" allows just the right amount of daylighting in the space, depending on the outdoor weather conditions. The daylighting can be coupled with daylighting sensors for light, which not only reduces energy consumption for lights, but also saves on cooling energy costs. The submission addresses this strategy.

Another strategy that the "Active Façade" submission would fit in is, "Assess Opportunities for a 'Whole Building' Approach." The active façade has implications which go beyond the obvious – the energy savings. It has implications for the building footprint, building occupants perception of the space, and, of course, the health and well being of the building occupants.

Biographies:

Faruq Ahmed is a Principal with the architecture, engineering, interiors, and applied research firm, Burt Hill Kosar Rittelmann Associates in Butler, Pennsylvania. Faruq is a registered professional engineer with over 36 years of engineering experience. He holds a Masters degree in Engineering from Colorado State University. His involvement in various engineering disciplines include: Alternative energy systems, including power generation technologies, information systems technology, communications systems, solar and renewable energy systems, energy conservation, and electric power quality and reliability. Faruq has been working on energy related projects, including renewable energy, since 1967. He is an active participant in various forums for Research Applied to Buildings and Systems. Faruq is the organization representative for the EPA Cooling Heating and Power (CHP) Partnership and for EDUCAUSE – the organization of technology professionals for higher education institutions. He has been a regular speaker at various Strategic Research Institute Conferences. He is also a frequent speaker at various conferences such as Tradelines, EPA Labs for the 21st Century, EDUCAUSE, SCUP, APPA, ERAPPA, SRAPPA and many others.

Dick Rittelmann is the Chairman of Burt Hill Kosar Rittelmann Associates, an architecture, engineering, interiors, and applied research firm in Butler, Pennsylvania. He is a graduate of Rensselaer Polytechnic Institute. Dick is a Fellow of American Institute of Architects. His involvement with Power Systems using Alternative Energy systems, dates back to the 1970's. During that time he was actively involved with various DOE activities for large-scale PV Systems and other Solar Energy projects. He has participated in the International Energy Agency (IEA) activities as U.S. representative for several tasks. He also participates on the Research Advisory Boards for many National Labs which include Lawrence Berkeley Lab and Oakridge National Lab. Dick is a highly sought speaker by various professional organizations such as Strategic Research Institute, Tradelines, AIA, ASHRAE, CIC, EPA Labs for the 21st Century, EDUCAUSE, APPA, ERAPPA, SCUP, AEC Systems, various Hospital Technology organizations, etc. He has been involved in presenting papers and seminars for over 40 years. His expertise, in addition to architecture for Mission-Critical Buildings, includes Information Systems, High Technology Medical Systems, Research Labs and Communication Facilities.

Jayesh Hariyani is an Associate and a lead architect in Burt Hill's high tech market sector. His artistic ability coupled with his technical capabilities creates a new dimension to visual presentations. He quickly and easily transforms design concepts into three-dimensional renderings. From his international experience, he is sensitive to the multi-cultural influences. He was the lead architect on the project being presented in this submission. Jayesh has been involved in many projects for residential development projects focusing on both research and design of community development and the sociological impact. He is Burt Hill's lead architect on the University of Texas Institute of Molecular Medicine Building in Houston and the Physical Sciences Building at Cornell University.

 

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