Page 29 - Zero Net Energy Case Study Homes-Volume 2

PASSIVE HOUSE LOS ANGELES (PHLA+)
CASE STUDY NO. 6
Natural Ventilation
As required for Passive House, windows are openable to provide natural ventilation, a valuable source of cooling in this mild climate.
Lighting and Plug Loads
Lighting, plug loads and domestic hot water constitute roughly 75% of the modeled energy use because of the high energy efficiency of the building envelope and the heating and cooling equipment. All lighting is done with high-efficiency LED sources.
Since the house is designed to be all-electric, the cooking is done by induction cooktop and electric oven. The clothes dryer is a condensation dryer, which requires no vent to the exterior, thereby avoiding potential air leakage via a wall penetration.
Control Systems
Control of all energy systems is done simply using the control apps for the individual systems resident on two iPads. The iPads are mounted in prominent locations on a wall in the living area of the first floor and in the hallway of the second floor. There is no wiring since the iPad is con- nected to the house wifi, and it is a simple matter to control the systems or check on their status from this location.
Construction
Construction required one year and was completed at the end of 2018. During construction, particular attention was paid to details that would affect the airtightness of the construction and the continuous insulation characteristics with regard to thermal breaks and thermal bridging. The construction trades were reminded regularly of the airtightness issue in the course of their work. (See construction site photos on p. 12.)
Renewable On-Site Energy Supply
The on-site solar PV system consists of only 16 Sunpower panels, each capable of producing 335 watts, for a total of 5.36 kW.
The system is also connected to one Tesla Powerwall battery with storage potential of 13.5 kWh. This battery provides a free energy source in the evening when the energy consumption tends to be high and there is no power being generated by the solar PV panels. It essentially provides a method of load-shifting, which has a benefit when the utility rate structure sets a higher rate in the evening compared with the rate in the middle of the day. The battery also ensures that the house will have an uninterrupted power supply in case of a power outage at any time on the utility grid.
(Left) 13.5 kWh battery is mounted on the exterior wall near the carport. (Photo by Christian Kienapfel)
Zero Net Energy Case Study Homes: Volume 2
15