Reference Publication: McIlvaine, J., Mallette, M., Parker, D., Callahan, M., Lapujade, P., Floyd, D., Schrum, L., Stedman, T., Cumming, B., Maxwell, L., Salamon, M., "Energy-Efficient Design for Florida Educational Facilities," Prepared for the Florida Department of Education, Tallahassee, FL., September, 2000. Disclaimer: The views and opinions expressed in this article are solely those of the authors and are not intended to represent the views and opinions of the Florida Solar Energy Center. |
Energy-Efficient Design for Florida Educational Facilities
Janet McIlvaine, Michele Mallette, Danny Parker, Michael
Callahan, Philippe Lapujade, David Floyd, Lynn Schrum,
Ted Stedman, Brian Cumming, Larry Maxwell, Milt Salamon
Florida
Solar Energy Center (FSEC), R. Douglas Stone Associates, Inc.,
Spacecoast Architects, Technical Editor
FSEC-CR-1682-00
Energy-Efficient Design for Florida Educational Facilities Homepage
Energy Analysis
The energy savings predictions in this manual were determined using
a building energy simulation program which uses a computer model of the
building and data on energy conservation measures (ECM) to predict annual
energy use, energy cost, required cooling capacvity, peak loads, and a
wide variety of other energy indicators. The quality of the program, the
computer building model, and the ECM data determines the validity of the
energy savings predictions. These are described in the following sections.
Simulation Program
The DOE 2.1E program used for the simulation work presented in this
manual ranks high among energy analysis tools in the energy research industry.
The U.S. Department of Energy developed the program in conjunction with
the Lawrence Berkeley Laboratory.(1)
Building Models
A variety of input data is required to simulate the annual energy use of a building. these include physical and operational characteristics as well as weather data. The research team endeavored to accurately represent current facilities characteristics in each area of input.
Building type: Three building-types were modeled: class-room building, administration (office) building, and multi-purpose building. In developing each of the three building models, the research team drew from a variety of sources including:
- State of Florida regulations for school construction
- Blueprints and specifications for recently built schools
- Conversations with operations staffs
- Discussion with designers and engineers involved with educational facilities
- Conversations with experts in building energy simulation.
Weather data: Each building was simulated using the weather data for 1989 for Orlando, FL (latitude 28.30, longitude 80.34, altitude 16). Beacuse energy use in educational facilities is dominated by internally generated loads, the variation of the weather conditions from North to South Florida is not as critical a parameter as it would be for an externally loaded building type, such as a residence. This is not intended to minimize the concern of those design teams building in climates other than central Florida. Time constraints however prevent the research team from executing all of the simulations for each section of Florida. However, the research team will be happy to produce runs (simulations) of any ECMs presented in htis text for a specific locaton within the constraints of available weather data.
Orientation: The long axis of all basecase models is aligned with the east-west axis. Major glazing areas face north and south. This bives the base case buildings the advantage of being well positioned for daylighting.
Materials and assemblies: The construction assemblies used for each model were the same:
Roof construction: Exterior finish of 3/8 inch built-up roofing (absorptance=0.75), R-11 rigid insulation (preformed mineral board) on quarter-inch deck with suspended acoustic tile. Deminision between roof top and ceiling finish is 3 feet.
Walls: Exterior walls are 4-inch medium-colored face brick (abs=0.60), air space, R-3 rigid insulation (expanded polystyrene), hollow lightweight concrete block, and air space (3/4-inch or less). The interior wall finish is gypsum or plaster board. Metal exterior doors have construction U-value of .25.
Glazing: All windows are 1/8-inch single pane clear. The glass has a shading coefficient of 1, visible light transmittance of .90, and glass conductance of 1.1.
Floor: Concrete slab with carpet and rubber pad.
Interior Conditions: Various interior characteristics must be defined; here, the three building types varied widely since activity, spatial characteristics, and occupancy varied. However, the three shared the following:
Occupancy: Base Case Building occupancy was assumed for the school year schedule from 7am-4pm. Some occupancy was modelled for summer and evening hours. Infiltration is defined at .35 ACH in the interior and plenum spaces.
Conditioning Set Points: The heating set points were 50 degrees (midnight to 6am) 72 degrees (6am-4pm), 65 degrees (4-6pm), 55 degrees 6pm-midnight). For weekends and holidays the heating set point was assumed to stay at 55 degrees 24 hours a day. The cooling set points were 90 degrees (midnight-6am), 76 degrees (6am-4pm), 85 degrees (4pm-6pm), and 90 degrees (6pm-midnight). For weekends and holidays, a setting of 90 degrees was maintained 24 hours a day.
Spatial characteristics:
Classroom building: The classroom building contains two rows of exterior-access classrooms (27 ft * 35 ft each) and a small core area for storage and/or office spaces (12 ft * length of building) between the two rows.
Administration building: The administration building houses a variety of private or semi-private offices, work and conference rooms, a break room, a supply room, a reception area and a library.
Multipurpose building: The multipurpose/assembly building consists of a dual use cafeteria-auditorium space with a kitchen at one end of the building and a stage (and storage) area at the other end.
Hypothetical campus: A campus composed of Base Case Building
types would include one multipurpose building, one administration building,
and 6 class- room buildings.
Energy Conservation Measures
Simulating ECMs requires the research team to deter-mine how an ECM affects the physical and operational characteristics of the building. For each ECM, para-meters in the Base Case Building input deck must be changed.
How does one know what to alter and how much to change it? If the simulation input data for an ECM does not agree with reality, the energy savings predictions will obviously be biased and misrepresentative.
As a consequence, the research team has endeavored to represent accurately the savings potential of various measures. This information was gleaned, whenever possible, from field or laboratory research data. When uncertainty existed, the research team selected conservative values for estimating the ECM benefits. The input changes for each ECM are documented in the following tables.
| MEASURE | CHANGED PARAMETER | SOURCE OF DATA* |
| Non-Optimal Orientation | Rotated building 90o. Long axis aligned with the North-South axis | 3 |
| Single Pane Reflective Glazing | SC = 0.51, VT = 0.27, gc = 1.12 | 1 |
| Double Pane Clear Glazing | SC = 0.89, VT = 0.82, gc = 0.50 | 1 |
| Double Pane Reflective Glazing Bronze | SC = 0.42, VT = 0.26, gc = 0.5 | 1 |
| Double Pane Spectrally Selective Glazing | SC = 0.36, VT = 0.61, gc = 0.33
Daylight "OFF", 1.4 W/sq.ft. |
4 |
| Ceiling Fans | Raised cooling set point 2 degrees
Raised equipment load 40 W per fan |
5 |
| 4 Foot Overhang | Added 4 foot building shade on all sides | 5 |
| Shade Trees | Added building shades to the East, West, and South sides of building to simulate shape of mature live oak | Florida Energy Extension Service |
| Roof Insulation (R-30) | Changed roof insulation R-value to 30 | 3 |
| Reflective Wall Finish | Changed wall absorptance from 0.6 to 0.4 | 4 |
| Light Shelves | Added buildind shades with 75% top reflectivity at 1/3 the height of the window from the top of the window on the South facade | This simulation does not reflect the complete effect of a lightshelf. |
| 2 Foot Overhang (roof) | Added 2 foot building shade on all sides | 3 |
| R-11 Wall Insulation | Changed wall insulation to R-11 (rigid to exterior of blocks) | 3 |
| R-19 Wall Insulation | Changed wall insulation to R-19 (rigid to exterior of blocks) | 3 |
| Interior Insulation | Moved wall insulation to interior of construction | 3 |
| 32 Watt T-8 Lamps Electric dimming ballast Parabolic troffer with reflector Prismatic diffuser |
Daylight "YES", Lighting W/sq.ft. = 1.06 | 2 |
| 32 Watt T-8 Bulbs Electronic ballast Parabolic troffer Open diffuser |
Lighting W/sq.ft. = 1.06 | 2 |
| 34 Watt T-12 Bulbs Magnetic ballast Parabolic troffer Open diffuser |
Daylight "OFF", 1.38 W/sq.ft. | 2 |
| 40 Watt T-12 Magnetic dimming ballast Parabolic troffer with reflector Open diffuser |
Daylight "YES", W/sq. ft. = 1.18 | 2 |
| 40 Watt T-12 Magnetic ballast Parabolic troffer with reflector Open diffuser |
Daylight "OFF", 1.52 W/sq.ft. | 2 |
| Occupancy Sensors | Reduced lighting watts per sq. ft. by 15% | 6 |
| LED Exit Signage | New lighting wattade from 40 W/single sided exit sign to 4.5 W |
4 |
| Centrifugal Chiller | Changed chiller type = open-vent-chlr | 3 |
| Screw Chiller | Changed chiller type = HIR, EIR, CAP = Quadratic Curve Fits |
3 DOE2.1E sample run book under direction of |
| Gas Absorption Chiller | Changed chiller type - single stage absorption chiller | 3 |
| Variable Speed Pumps | CCIRC-Pump-Type = Variable-Speed
HCIRC-Pump-Type = Variable-Speed |
3 |
| Non-Variable Speed Fans | O/A Control = Fixed | 3 |
| Variable Temperature Constant Volume | Changed System Type to SZRH | 3 |
| Multizone Constant Volume | System Type = MZS | 3 |
| Dual Duct Constant Volume or Variable Volume | System Type = DDS | 3 |
| Four Pipe Fan Coil | System Type = FPFC | 3 |
| 15 cfm per person ventilation rate | OA CFM = 15 | 3 |
| Total Energy Recovery System for 5 cfm ventilation rate | OA CFM=2 | Simulations of sensible and latent heat recovery per-formed by K. Rengarajan, Florida Solar Energy Center |
| Total Energy Recovery System for 15 cfm ventilation rate | OA CFM=6 | |
| Optimal Start (Energy Management System) |
Cooling Set Point Schedule on weekdays =-999 for start hours | 3 |
| Enthalpy Economizer | OA Control = enthalphy
Econo limit T=50 |
3 Consultation with Brian Cumming, R. Douglas Stone Assoc., Orlando, FL. |
| Reheat Constant Volume | System Type = RHFS
Max - humidity = 60 Reheat - delta-T = 55 |
3 |
| Unitary Heat Pumps | System Type = HP | 3 |
| Packaged Single Zone Variable Temp Dx Unit | System Type = PMZS
Heat - source = electric |
3 |
| Packaged Multizone Dx Unit | System Type = PSZ
Heat - source = electric |
3 |
| Packaged Terminal AC/Heat Pump | System Type = PTAC
Heat - source = electric |
3 |
* 1 = Parker, 1989; 2 = Parker, et.al., 1994; 3 = DOE2.1E
Manuals; 4 = Manufacturer data; 5 = Discussion with energy simulation experts;
6 = Educated guess
Further Questions
Requests for additional information should be directed to Danny Parker,
Florida Solar Energy Center, 1679 Clearlake Road, Cocoa, FL 32922-5703
1. A PC version of DOE 2 is available from ITEM Systems in Berkeley, CA, (510)549-1444 for the cost of about $700. Several other PC versions of DOE-2 are available. Mainframe versions of DOE 2 are available from the Simulation Group at Lawrence Berkeley Laboratory (510)486-4000.
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