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7.A. - Page 192 of 285 2019 Nonresidential New Construction Reach Code Cost Effectiveness Study <br />Figure 9. All -Electric HVAC and Water Heating Characteristics Summary. <br />The Reach Code Team received cost data for baseline mixed -fuel equipment as well as electric equipment <br />from an experienced mechanical contractor in the San Francisco Bay Area. The total construction cost <br />includes equipment and material, labor, subcontractors (for example, HVAC and SHW control systems), <br />and contractor overhead. <br />3.3.1.1 Medium Office <br />The baseline HVAC system includes two gas hot water boilers, three packaged rooftop units, and VAV hot <br />water reheat boxes. The SHW design includes one 8.75 kW electric resistance hot water heater with a 30 - <br />gallon storage tank. <br />For the medium office all -electric HVAC design, the Reach Code Team investigated several potential all - <br />electric design options, including variable refrigerant flow, packaged heat pumps, and variable volume <br />and temperature systems. After seeking feedback from the design community, the Reach Code Team <br />determined that the most feasible all -electric HVAC system, given the software modeling constraints is a <br />VAV system with an electric resistance reheat instead of hot water reheat coil. A parallel fan -powered box <br />(PFPB) implementation of electric resistance reheat would further improve efficiency due to reducing <br />ventilation requirements, but an accurate implementation of PFPBs is not currently available in <br />compliance software. <br />Note that the actual natural gas consumption for the VAV hot water reheat baseline may be higher than <br />the current simulation results due to a combination of boiler and hot water distribution losses. A recent <br />research study shows that the total losses can account for as high as 80 percent of the boiler energy use.19 <br />19 Raftery, P., A. Geronazzo, H. Cheng, and G. Paliaga. 2018. Quantifying energy losses in hot water reheat systems. Energy and <br />Buildings, 179: 183-199. November. https://doi.org/10.1016/i.enbuild.2018.09.020. Retrieved from <br />https://escholarship.org/uc/item/3gs8f8gx <br />17 <br />RE <br />2019-07-25 <br />444 <br />Medium Office <br />Medium Retail <br />Small Hotel <br />Non Res: Packaged DX + VAV with <br />Packaged DX + VAV <br />Single zone <br />HW reheat. Central gas boilers. <br />Baseline <br />with HW reheat. <br />packaged DX with <br />HVAC <br />Central gas boilers. <br />gas furnaces <br />Res: Single zone DX AC unit with <br />System <br />gasfurnaces <br />Packaged DX + VAV <br />Single zone <br />Non Res: Packaged DX + VAV with <br />Proposed All- <br />with electric <br />packaged heat <br />electric resistance reheat <br />Electric <br />resistance reheat. <br />pumps <br />Res: Single zone heat pumps <br />Non Res: Electric resistance <br />Electric resistance <br />Electric resistance <br />storage <br />Water <br />Baseline <br />with storage <br />with storage <br />Res: Central gas storage with <br />Heating <br />recirculation <br />System <br />Proposed All- <br />Electric resistance <br />Electric resistance <br />Non Res: Electric resistance <br />Electric <br />with storage <br />with storage <br />storage <br />Res: Individual heat pumps <br />The Reach Code Team received cost data for baseline mixed -fuel equipment as well as electric equipment <br />from an experienced mechanical contractor in the San Francisco Bay Area. The total construction cost <br />includes equipment and material, labor, subcontractors (for example, HVAC and SHW control systems), <br />and contractor overhead. <br />3.3.1.1 Medium Office <br />The baseline HVAC system includes two gas hot water boilers, three packaged rooftop units, and VAV hot <br />water reheat boxes. The SHW design includes one 8.75 kW electric resistance hot water heater with a 30 - <br />gallon storage tank. <br />For the medium office all -electric HVAC design, the Reach Code Team investigated several potential all - <br />electric design options, including variable refrigerant flow, packaged heat pumps, and variable volume <br />and temperature systems. After seeking feedback from the design community, the Reach Code Team <br />determined that the most feasible all -electric HVAC system, given the software modeling constraints is a <br />VAV system with an electric resistance reheat instead of hot water reheat coil. A parallel fan -powered box <br />(PFPB) implementation of electric resistance reheat would further improve efficiency due to reducing <br />ventilation requirements, but an accurate implementation of PFPBs is not currently available in <br />compliance software. <br />Note that the actual natural gas consumption for the VAV hot water reheat baseline may be higher than <br />the current simulation results due to a combination of boiler and hot water distribution losses. A recent <br />research study shows that the total losses can account for as high as 80 percent of the boiler energy use.19 <br />19 Raftery, P., A. Geronazzo, H. Cheng, and G. Paliaga. 2018. Quantifying energy losses in hot water reheat systems. Energy and <br />Buildings, 179: 183-199. November. https://doi.org/10.1016/i.enbuild.2018.09.020. Retrieved from <br />https://escholarship.org/uc/item/3gs8f8gx <br />17 <br />RE <br />2019-07-25 <br />444 <br />