Potential Energy Savings Chart Validation Study

Green Building Studio's (GBS) PES feature automatically initiates a set of 37 separate energy simulations that are run simultaneously in the cloud. See the Potential Energy Savings Chart topic for more details about this feature, and the Alternative Runs (Details) for details about each parameter.

Parameter Name Description
Plug Load -- Low Efficiency 100% increase over baseline
Plug Load -- High Efficiency 40% reduction below baseline
Lighting -- Low Efficiency ASHRAE 2001 standard
Lighting -- High Efficiency 63% reduction below ASHRAE 2001 baseline
Building Orientations _(-)135 Orientation direction (negative value is counter-clockwise, positive value is clockwise), and degree of rotation from project north. Rotated so that project north faces Southwest.
Building Orientations _(-)90 Project north faces West
Building Orientations _(-)45 Project north faces Northwest
Building Orientations _(+)180 Project north faces South
Building Orientations _(+)135 Project north faces Southeast
Building Orientations _(+)90 Project north faces East
Building Orientations _(+)45 Project north faces Northeast
Occupancy Sensors - On Based upon ASHRAE 90.1 for all spaces <= 5000 sq ft, reduce Lighting Power Density (LPD) 15%
for all other spaces reduce LPD 10%
Occupancy Sensors - Off Same LPD as the baseline
Window Glass w/DC _BaseRun_w/DC Applies daylilghting controls with the base run window glass characteristics.
Daylight Controls - Off Same LPD as the baseline
Roof Insulation -R-60 continuous insulation Wood Frame Roof with R-60 insulation
Roof Insulation - Uninsulated Metal Frame Roof without Insulation
Skylight Glass w/DC _Quad_Kryp_Clear_w/DC Daylighting controls and skylight glass properties: low thermal heat transmission (U-0.12), moderate solar heat gain (0.45), high visible light transmittance (0.62)
Skylight Glass w/DC _Dbl_LowE_HP_w/DC Daylighting controls and skylight glass properties: low thermal heat transmission (U-0.29), low solar heat gain (0.27), high visible light transmittance (0.64)
Skylight Glass w/DC _Triple_LowE_film_w/DC Daylighting controls and skylight glass properties: low thermal heat transmission (U-0.31), low solar heat gain (0.2), low visible light transmittance (0.22)
Skylight Glass w/DC _Single_Low_Iron_w/DC Daylighting controls and skylight glass properties: high thermal heat transmission (U-1.11), high solar heat gain (0.9), high visible light transmittance (0.91)
Window Glass w/DC _Quad_Kryp_Clear_w/DC Daylighting controls and window glass properties: low thermal heat transmission (U-0.12), moderate solar heat gain (0.45), high visible light transmittance (0.62)
Window Glass w/DC _Dbl_LowE_HP_w/DC Daylighting controls and window glass properties: low thermal heat transmission (U-0.29), low solar heat gain (0.27), high visible light transmittance (0.64)
Window Glass w/DC _Triple_LowE_film_w/DC Daylighting controls and window glass properties: low thermal heat transmission (U-0.31), low solar heat gain (0.2), low visible light transmittance (0.22)
Window Glass w/DC _Single_Low_Iron_w/DC Daylighting controls and windowglass properties: high thermal heat transmission (U-1.11), high solar heat gain (0.9), high visible light transmittance (0.91)
Skylight Glass _Quad_Kryp_Clear Skylight glass properties: low thermal heat transmission (U-0.12), moderate solar heat gain (0.45), high visible light transmittance (0.62)
Skylight Glass _Dbl_LowE_HP Skylight glass properties: low thermal heat transmission (U-0.29), low solar heat gain (0.27), high visible light transmittance (0.64)
Skylight Glass _Triple_LowE_film Skylight glass properties: low thermal heat transmission (U-0.31), low solar heat gain (0.2), low visible light transmittance (0.22)
Skylight Glass _Single_Low_Iron Skylight glass properties: high thermal heat transmission (U-1.11), high solar heat gain (0.9), high visible light transmittance (0.91)
Window Glass _Quad_Kryp_Clear Window glass properties: low thermal heat transmission (U-0.12), moderate solar heat gain (0.45), high visible light transmittance (0.62)
Window Glass _Dbl_LowE_HP Window glass properties: low thermal heat transmission (U-0.29), low solar heat gain (0.27), high visible light transmittance (0.64)
Window Glass _Triple_LowE_film Window glass properties: low thermal heat transmission (U-0.31), low solar heat gain (0.2), low visible light transmittance (0.22)
Window Glass _Single_Low_Iron Window glass properties: high thermal heat transmission (U-1.11), high solar heat gain (0.9), high visible light transmittance (0.91)
Wall Insulation - R-44 Structurally Insulated Panel (SIP) Wall 12.25 inches (311 mm) thick, 48 inch on-center R-44 insulation
Wall Insulation - Uninsulated Metal Frame Wall without Insulation
Infiltration _3.5_ACH Very loose envelope with 3.5 air changes per hour at 10 wind speed of mph
Infiltration _0.17_ACH Very tight envelope with 0.17 air changes per hour at 10 wind speed of mph

Validation Methodology. In order to fully test and validate the PES results, the GBS energy analysis and building science subject matter expert (SME) team ran a total of more than 171,000 energy simulations runs, covering 17 climate locations, 34 building types, 4 simplified Vasari conceptual models, and 37 parameters, with model projects units using both IP and SI units. The rationale behind using such a broad set of variations was two-fold: GBS generates a different set of baseline inputs for some building parameters based upon the building size, height, type, and location; and all of these variations will have differing sensitivities to the 37 PES parameters.

Refer to the GBS WikiHelp topic, GBS Default Values per Building Type and Building Assumptions and Details for more information on the baseline defaults.

Location ASHRAE Climate Zone
Rio de Janeiro, Brazil 1A
Caracas, Venuzuela 1B
Brasilia, Brazil 2A
Cairo, Egypt 2B
Sydney, Australia 3A
Crete, Greece 3B
Addis Abada, Ethiopia 3C
Nantes, France 4A
Albuquerque, NM 4B
Seattle, WA 4C
Glasgow, Scotland 5A
Uyrgur, Xinjiang, China 5B
Ankara, Turkey 5C
Ottowa, Canada 6A
Rock Springs, WY 6B
Ukhta, Russia 7
Krasnoiarsk, Russia 8

Building Type

Select results of the simulation runs were automatically extracted into a spreadsheet, such as the total energy end use (EUI) for each run, the annual electric, and the annual fuel usage.

Pivot table and charts were generated from this set of results, which allowed the GBS team of building science experts to quickly review the results by slicing the data into various segments. The chart below is an example of EUI results for the window glass parameters for an office building with the small one-story model, across all 17 climate zones. The SME's applied their expertise in the building science and energy analysis field to ascertain whether or not the results are expected and make sense. In this example the expected result is that the baseline run's EUI (black horizontal bar) would fall somewhere in the middle of the range of glass parameter results (vertical gray bars).

The full set of our validation runs is available for download (PES Validation IP Units, PES Validation SI Units).

Pivot Table Chart Example. Window Glass parameters, Office, small one-story building

Pivot Table Chart Example. Lighting Efficiency parameters, Hotel, large one-story building

Parametric validation model: 4466 sq feet (415 sq meters), 4 stories, 2% skylight to roof area, 40% window to wall area

Deeper analyses were then performed on hundreds of specific results from a comprehensive cross-section of samples The SMEs used a combination of detailed results from GBS pages, weather data, and DOE-2 .inp files (automatically generated by GBS) to validate the inputs and the expected comparative results.

Comparisons of the baseline runs to the parametric runs were made to ensure that each parametric feature was correctly modeled. In not all cases is the EUI the best metric for comparisons; in some instances a better measure of comparative results might be the total energy costs, the total annual electricity usage, or the total annual fuel usage. This is due to the energy trade-offs in some parameters; for example decreasing the lighting power density will reduce the annual electricity consumption but may increase the fuel usage for heating in many cases

For the orientation parametric runs, the .inp models were imported into eQUEST to visually inspect the resulting model orientation.

Parametric validation model: 3658 square feet (340 sq meters), one story, 2% skylight to roof area, 40% window to wall area.