DESIGN AND EVALUATION OF ENERGY-EFFICIENT MODULAR CLASSROOM STRUCTURES, PHASE II G. Z. Brown, Dana Bjornson, John Briscoe, Sean Fremouw, Jeff Kline, Pa wan Kumar, Paul Larocque, Dale Northcutt, Zhunqin Wang Energy Studies in Buildings Laboratory Department of Architecture University of Oregon, Eugene, OR 97403 ABS1RACT We are developing innovations to enable modular builders to improve the energy performance of their classrooms with a minimum increase in first cost. The Modern Building Systems' (MBS) classroom building conforms to the stringent Oregon and Washington energy codes, and at $18/S.F. (FOB the factory) it is at the low end of the cost range for modular classrooms. We are investigating daylighting, cross-ventilation, solar preheat of ventilation air, electric lighting controls, and down-sizing HV AC systems. The work described in this paper is from the second phase of the project. In the first phase we redesigned the basic modular classroom to include energy efficiency features tailored to five distinct climates. Energy savings ranged from 6% to 49% with an average of 23%. Paybacks ranged from 1.3 yrs to 23.8 yrs, an average of 12.1. The initial work in Phase II (which added two more climates) has been to refine the designs for each of the seven climates and reduce payback periods. In Phase II the number of baseline buildings was expanded by simulating buildings that would be typical of those produced by MBS for each of the seven locations/climates. A number of parametric simulations were performed for each energy strategy. Additionally we refined our previous algorithm for a solar ventilation air wall preheater and developed an algorithm for a roof preheater configuration. These algorithms were coded as functions in DOE 2. lE. Donald Rasmussen, Kenneth Rasmussen, James Stanard Modern Building Systems, Inc. 9493 Porter Road, Aumsville, OR 97325 savings. We performed computer analyses to verify adequate illumination on vertical surfaces and acceptable glare levels when using daylighting. We also used computational fluid dynamics software to determine air distribution from cross­ ventilation and used the resulting interior wind speeds to calculate occupant comfort and allowable outside air temperatures for cross-ventilation. To choose the final mix of energy strategies, we developed a method to compare incremental costs versus energy savings for all strategies at once. The results of parametric energy simulations were graphed against detailed cost information. This allowed us not only to easily see which broad strategies were most cost effective but also to choose the best configurations of the strategy. Final results were obtained by simulating the strategies chosen from the cost/energy graphs. In some cases adjustments were made in the chosen strategies since the final performance is not readily predictable from parametrics of many systems. RESEARCH CARRIED OUT In Phase I we redesigned the basic unit to incorporate energy strategies including daylighting, cross-ventilation, solar preheating of ventilation air, and insulation. We also explored thermal mass but determined that it was not a cost­ effective strategy in the five climates we examined. The basic unit before redesign consists of two 14 'x64' modules that are put together on site to create two 28'x32' We were aiming for occupant comfort as well as energy classrooms. Wall insulation is R 11, roof insulation R30, 10157/PP97-1:jk ASES Solar Conference '97 Washington D.C. Page 1 of 6 3 ton heat 24'-0" 24'-0" pump 0 ..... � ..... 0 ' ..... t-' � ..... 32'-0" 32'-0" 64'-0" �11111111111m11111111□1□1111111�11111111111r Front - End Fig. 1: Baseline Unit and floors R19. Each classroom has one 4'x4' window, fluorescent lighting and one 3-ton heat pump; see fig. 1. We tailored energy strategies for each of the five locations we explored: Fairbanks AK, Spokane WA, Astoria OR, Bakersfield CA, and Honolulu ID. The climates chosen reflect MBS 's primary markets. Starting with a single baseline design that meets Oregon and Washington energy codes we achieved annual energy savings of 6% to 49% with simple paybacks of 1.3 years to 23.8 years. Fig. 2 shows the classroom unit design after Phase I. In Phase II our goal is to improve payback periods. Our plan is to choose strategies for each climate that produce paybacks between 5 and 10 years. We have added Phoenix AZ and Miami FL to our study locations in order to make our results inclusive of the major climates in the United States, although MBS does not market in these areas. To make the results as accurate as possible, we created separate baseline buildings typical of the type of unit that MBS would actually ship to each location. We therefore repeated the Phase I simulations and cost analyses for the original five climates and added two more sets of analyses for the Classroom 32x28 Classroom 32x28 ' ' ' ' ' l_l!::,,,c,=,1::= ,=,,=,="=,::c:,=,,:i:,�,,= ,=,,= ,::!:,!:::"=,=�=�c,=,i::,,==,,=,=,=,,::c:,=,,:::i:,::!I. � Canopy Plenum above North Preheat /.. Pane17 �m Alternate Panel Sections Damper\ Unit � ,- Air Bypass HVA::GHC Supply ,,, l'.1:/'/� Return -Air m Preheat Panel Preheater Air Flow Diagram Preheater Wall Section Fig. 2: Basic Unit with Energy Features, Phase I new locations. For each climate we performed over 300 parametric simulations and cost analyses. Another goal of Phase II is to address several occupant comfort issues, including visual comfort, and verify that cross-ventilation is effective in cooling all occupants of the rooms while not creating discomfort by introducing cold air at high velocities. ENERGY STRATEGIES Phase I results suggested that the cost-effectiveness of the solar vent air preheater was questionable in several climates. 10157/PP97-1:cb ASES Solar Conference '97 Washington D.C. Page 2 of 6 0 year $250 Phoenix, AZ 2,500 $200 � $150 '° ,..., 0 ,..., 0 � $100 � $50 Ul