Page 116 - Zero Net Energy Case Study Homes-Volume 2

CASE STUDY NO. 11 SOL LUX ALPHA
Sol Lux Alpha
Case Study No. 11
Data Summary
Building Type: Multifamily – Mid-Rise (New Construction)
Location: San Francisco, CA Gross Floor Area: 12,225 gsf Occupied:
Unit A: 2016; Unit B: 2016 Unit C: 2019; Unit D: 2018
On-Site Renewable Energy System Installed:
Each Unit: 10 kW (DC)
On-Site Storage Battery
Each Unit: 3 Tesla Power- Walls, 40.5 kWh
Measured On-Site Energy Production:
Unit A: 11,686 kWh per year 17.3 kBtu/sq.ft. per year Unit B: 11,077 kWh per year
16.37 kBtu/sq.ft. per year Unit D: 11,417 kWh per year
16.88 kBtu/sq.ft. per year
Pre-Occupancy Calculated EUI (Site):
Whole Building: 8.05 kBtu/ sq.ft. per year
Measured EUI (Site):
Unit A: 14.66 kBtu/sq.ft. per yr Unit B: 15.57 kBtu/sq.ft. per yr Unit D: 13.25 kBtu/sq.ft. per yr
Owner/Client
Sol Lux Alpha LLC, San Francisco, CA
Project Team
Architect:
RG-Architecture, San Francisco, CA
Mechanical Engineer Design:
Neumann Energy Design, San Francisco, CA
Electrical Engineer:
Zeiger Engineers, Oakland, CA
Certified Passive House Consultants:
Graham Irwin, San Anselmo, CA
Air-Sealing Consultant:
Terry Nordbye, Inverness, CA
General Contractor:
Sarter Construction & Design, San Rafael, CA
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There is another type of multifamily housing commonly built in California urban areas, which has proved challenging to the production of projects with zero-net-energy (ZNE) performance. This is the developer-initiated luxury condominium project. With the recent inflation of the cost of construction in California, the financing of these projects and the resulting sale prices required to maintain adequate profit margins have affected the market size. The market is still a healthy one, however, especially in urban areas where high housing demand is a factor.
A for-profit developer of these types of projects is certainly inspired to undertake a ZNE project by a personal commitment to the general social goal of energy-efficient building and the conse- quent reduction of carbon emissions. But there are also profit-related advantages such as mar- keting and likely quick sale to buyers that are attracted to such a project. Another advantage that affects the bottom line is an expedited approvals process and favorable zoning interpretations by city agencies that consider ZNE projects desirable. This latter can result in a large reduction in the time to secure the necessary entitlements and project approvals—a great incentive for all developers. This case study is an example of such a project.
Finally, the Sol Lux Alpha project is instructive as a case study because it is an example of a mid- rise multifamily residential project that meets the Passive House Standards. As the third Passive House in this Volume 2, it employs the highly energy-efficient techniques required for Passive House certification1, while at the same time achieves ZNE performance and meets the financial objectives of the project.
Background
One of the developers was inspired to attempt a residential project that combined together the energy-efficiency building of the Passive Building Standard – North America2 with the latest renewable energy technologies, including enough additional on-site electric energy generation and battery storage to charge an electric vehicle (EV). This ambitious program goal was under- taken in a neighborhood just south of downtown San Francisco, which was expected to have the seller’s market and city agencies that would be favorable to such a project. Adding to the attractive location factors was the high purchase rate paid by CleanPowerSF for energy sent to the utility grid, $.089/kWh.
Besides these good marketing factors, the project would have one more attractive feature for both buyers and the public utility; namely, enough energy storage that would give the project a resiliency in the event of utility power shutdowns, either planned or unplanned. The individual living units would be able to function without any power interruption for an extended period of time, depending on capacity of the battery system in each unit. In the three years since the con- dominiums were placed on the market, this has proved to be a prescient design feature to have incorporated.
Once these guiding goals were established, a candidate project site in the locale was evaluated for the related factors of acquisition, program fit and financials. The site potentially available was a small empty residential lot (25 feet by 100 feet), which was privately owned but being used informally as a community garden. The owner of the property, hearing about the nature of the
1 For a description of the Standards for Passive House certification, see: https://www.passive- house-international.org/index.php?page_id=150.
2 The project was certified by Passive House Institute US (PHIUS) in 2016. https://www.phius. org/phius-2015-new-passive-building-standard-summary. It also received certification by the DOE Zero Energy Ready Home program. These certifications allowed the project to comply with San Francisco’s rigorous Green Building Code using the “alternate path of compliance”, saving additional time and expense. A LEED certification was not pursued.
Zero Net Energy Case Study Homes: Volume 2