Scenario two takes the building described in the ‘Business as Usual’ case and includes many simple improvements to equipment that significantly reduce the energy use in the building. Many retail projects targeting LEED certification employ these upgrades. Using proper sizing is not taken into consideration with this scenario. From the standard equipment from the initial design, this scenario includes heat recovery on ventilation air, skylights and daylighting sensors. The rooftop units have also been improved from a standard efficiency unit to a high efficiency unit such as the Lennox Energence unit. Additionally, all envelope components have been improved to further reduce the loads in the space. The key building components are summarized with a prescriptive target in the table below.
Table 5: 4 Typical Upgrades Prescriptive Summary
Assuming an average utility rate of $0.10/kWh for electricity, $0.25/m³ for natural gas, and $0.004/ekWh for purchased offset, the estimated utility costs for the ‘Typical Upgrades’ building are summarized along with the economics of including PV in the following table.
Table 6: Typical Upgrades Cost Summary
To ensure that 51% of the site energy use is covered by onsite generation, the ‘Typical Upgrades’ case will require 13.4 kW of roof mounted PV with 51.6 kW of parking lot mounted PV (4 units at 12.9 kW each). The area required for the ground mounted PV will take up approximately 32 parking spaces. An estimation of the layout required is presented below.
Figure 5: 4 Typical Upgrades PV Array
Directly comparing the ‘Typical Upgrades’ scenario to the ‘Business as Usual’ scenario, the effects of the upgraded building components can be explored in more detail with the aid of the following graphic.
Figure 6: 4 Energy End Use 4 Business as Usual vs. Typical Upgrades
Domestic Hot Water – Between the two scenarios, domestic hot water sees a reduction of approximately 70%. This is a direct result of the inclusion of low-flow fixtures in place of standard flow fixtures.
Fans - In spite of the addition of the energy recovery unit (ERV) which adds additional fans, the associated power sees a reduction of approximately 20%. This reduction is due to the upgrade from a standard efficiency rooftop unit to the Lennox Energence unit.
Space Cooling - Cooling energy sees a decrease of approximately 25%. This is due to a number of factors, including upgraded envelope components, the addition of the ERV and the switch to Lennox Energence units. The clearest conclusion to draw is that the importance of selecting the high efficiency rooftop unit is not based on the increase in EER, but rather the decrease in fan power.
Space Heating - The largest absolute drop, space heating (including outdoor air heating) sees a drop of approximately 66%. Some of this decrease is due to the improved envelope performance; however, the majority is due to the inclusion of the ERV.
Miscellaneous Equipment – Miscellaneous equipment does not change, as the assumption is that interior equipment required to run the store will not change with improvement to the HVAC equipment or building envelope.
Lighting - Lighting sees approximately a 30% decrease in energy use solely from the inclusion of skylights and continuous dimming lighting fixtures tied to daylighting sensors.