1. DISCLAIMER: THIS ANALYSIS IS BASED ON CONCEPTUAL DATA AND NOT TO BE USED FOR DESIGN OR CONSTRUCTION.
ACTUAL FINAL DESIGN AND PERFORMANCE WILL VARY.
2. Note: Conventional boiler sizes are calculated using the load profiles that are appropriate for each location and building type.
3. Energy calculations are taken from ASHRAE 90.1 (2013) Appendix G: Performance rating method for pumping power and fan power. The pumping and fan power is calculated in the same manner for all systems. Cooling energy is a function of peak cooling load, heat pump efficiency and total cooling hours. Heat pump efficiency for the GSHPs is 25 EER / 7.3 COP. The annual heating or cooling hours are calculated from the sum total energy (Btu) and peak load. The heating energy is calculated from the annual heating hours, peak heating load, 95% condensing boiler efficiency, and natural gas energy content taken from eia.gov of 1035 Btu/cu. ft. Energy costs are calculated from the energy consumption values and the user-input energy costs.
4. For systems incorporating a cooling tower, the cooling tower energy is estimated using annual cooling hours, peak cooling loads, and the input electricity rate. This model uses minimum cooling tower efficiency as prescribed in ASHRAE 90.1 (2010) 6.8.1-7.
5. Values are entered in $/kWh (kilowatt-hour). This program does not make use of time of day rates. By default, $0.10/kWh is used. If a rate is known, it may be entered in the "Rate for electric" input box.
6. The geothermal cost in $/sq ft is used with the total lineal feet of borefield pipe to calculate the entire cost of installing the borefield, pipes, grouting, pressure testing, flushing, filling, trenching, stubbing up into the building, and capping. The default value is $14/bore-foot. If a different value is desired, it can be input in the "Geothermal Installation Cost" input box.
7. Enter the total unit cost in $/sq. ft. for inside costs such as ductwork, grilles, registers, diffusers, etc. All equipment, except for the chiller and boiler, is considered inside installed costs and applies to ‘Conventional system cost’.
8. Select the amount of load variance. This is the difference between design load and actual load.
9. This is the lag, in hours, in which the peak load occurs. The model assumes that peak load typically coincides with peak outdoor air temperature, somewhere between 3 and 6 PM. If later, enter that value here.
10. By default, no boiler is used in the Greensleeves solution, unless the Use Boiler Checkbox is selected. The hybrid BAS solution uses the same components as the GS Connect (Greensleeves) solution so equipment size will be equal.
If the box checked and a percentage is selected from the dropdown, the selected percentage of load will be removed from the peak heating load. For example, if 15% is selected, then the heat pump will absorb 85% of the heating load and the boiler will absorb 15% of the heating load.