By Sunshine Mathon December 22, 2013
Since 1990, Foundation Communities (FC) has acquired and rehabbed, or at times built from the ground up, more than 2,700 high-quality apartments for low-income families and individuals throughout central Texas.
We will add another 300 to 400 apartments over the next two years and are planning a similar rate of growth in the years ahead. When residents sign a lease on a FC apartment, they are offered a broad range of on-site support services, including educational, financial and healthy living programs collectively designed to provide a stable platform for personal success.
For the last decade, as the result of benefiting from the placement of a Rose Fellow and as our portfolio and breadth of services have grown, green building has become a non-negotiable, critical aspect of FC’s development plans, both rehab and new construction, as well as our operations and maintenance strategies.
As a permanent owner, we fundamentally require durable properties with low utility costs and a healthy environment for staff and residents. Setting aside our mission to provide high-quality affordable housing where residents can take pride in their homes, building green makes bottom-line economic sense.
These essential considerations, as well as access to public transit and other site-related best practices, structured the design and development of Arbor Terrace, a 120-unit supportive housing property for single adults making 30 percent or less of median family income.
The Existing Building
In early 2011, the Texas Department of Housing and Community Affairs put out a call to developers to find abandoned or foreclosed properties to redevelop as affordable housing. We found a 10-year-old extended-stay motel in South Austin that was to be liquidated. Within a few short months, we had the property under contract and funding in place to perform a rehab transformation, turning a poorly aging 135-unit motel into a supportive housing community with 120 efficiency apartments coupled with robust resident services and community spaces.
The motel, in its original form, was a three-story, stick-built (2×4) T-shaped building with a slab-on-grade foundation. The walls were sided primarily with vinyl siding (with some stone façade), punctured by cheap, inefficient aluminum windows and old inefficient PTACs for heating/cooling each hotel room. The wall cavities were filled, unsurprisingly, with R13 fiberglass batts that were in better condition than I expected. The attic had a moderately acceptable 6 to 8 inches of loose-blown fiberglass and was actually vented fairly well. The bathrooms were vented with centralized continuous fans — sort of, anyway. All the fan belts were broken. The rooms had small kitchenettes that were in very poor condition, but at least all the plumbing and electrical was in place for conversion to apartments.
Though developing a HERS model for an existing 58,000 square foot “residential” building is a wee bit challenging, we utilized the process as a diagnostic tool, identifying gaps and clarifying our strategies to improve the thermal envelope. We initially tore off the aging vinyl siding and the poorly installed building wrap lying beneath. We then removed the existing windows, PTACS and PTAC sleeves. We then effectively re-sheathed the building using 1-inch ZIP R panels (1-inch polyiso insulation laminated onto 5/8-inch OSB with integrated waterproofing). At R6.6, the panels added an important continuous insulation layer outside the studs.
Given that the building had no effective window overhangs, and that a majority of the windows faced east and west (the most critical solar heat gain directions in our climate/latitude), we installed new vinyl windows (0.29 U-value and 0.29 SHGC) with full-size exterior solar screens, effectively reducing SHGC to 0.14.
In addition to these important thermal improvements, the most significant enhancement to the durability of the building, in my opinion, resulted from the opportunity to properly seal and flash all the exterior wall penetrations as if it were new construction.
At the apartment level, though we examined other solutions, we ultimately installed new Amana PTACs and PTAC sleeves. Though they didn’t have the highest energy-efficiency ratio available, we specifically chose Amana because they provided central control that no one else could match. We can log in online, change set points, control max/min temperatures, receive automated maintenance warnings, etc. This background control allows us to minimize peak usage and to maintain the equipment properly.
When we replaced the belts on the centralized exhaust fans, it became clear the apartments were being exhausted at two to three times the rates required by code. These high rates meant significant energy penalties due to increased infiltration of untreated air. In the end, we replaced the fixed-speed fans with variable speed fans with ECM motors. We fine-tuned the exhaust rate in each apartment with individual dampers.
Finally, in the process of converting 15 of the motel units into common area spaces (common eating area, game room, exercise room, support service offices, etc.), we replaced, or added, all common area HVAC with 16 SEER air-source heat pumps.
The existing shingle roof was in passable condition, but likely had only a few years of life left. Aiming for durability and hoping to install solar at some point in the near-term, we installed a new metal standing seam roof. This decision turned out to be prescient.
Due diligence during acquisition only gets you so far. Our construction budget of $3.5 million included a hefty contingency to cover the unexpected costs that inevitably arise in a rehab. However, the remodel proceeded remarkably smoothly. Nearing the end of construction, it became clear that we had a substantial pot of unspent money from our contingency budget. So just as construction was completing, we excitedly put out an RFP for a sizable solar array to be installed on our new metal roof.
Since 2005, when Austin Energy initiated one of the most robust municipal solar incentive programs nationwide, FC has installed solar electric and/or solar water-heating systems on every newly acquired or built property. In fact, at times, FC has been the largest private owner of solar in Austin. By the time we began work at Arbor Terrace, we owned approximately 150 kilowatts (kW) of solar electric in aggregate and almost 50 solar water-heating arrays.
Partway through 2012, Austin Energy made an important decision to increase the cap on its commercial solar electric incentives tenfold to 200 kW AC. With this expansion and with the available remaining budget we had, we were able to obtain a bid for a 76.25-kW DC array at $2.88 per watt utilizing ET Solar 245-watt panels and Enphase microinverters.
As a nonprofit, we cannot take advantage of the 30 percent federal investment tax credit. The above pricing, coupled with Austin Energy’s Performance-Based Incentive of $0.14 per kilo-watt-hour for 10 years, resulted in an estimated payback period (assuming 3.2 percent annual energy cost increases) of 7.5 to 8.5 years. The uncertainty in this estimate derives from the fact that Arbor Terrace is master- metered on a demand-based meter. On similar buildings that we own, about 50 percent of our electric bill is determined by the peak 15-minute demand (kW) for that monthly billing cycle. Though we expect a rough correlation between peak production for the west-facing portion (34.3 kW) of the array and the peak of the building’s demand profile, the estimate is just that, an estimate.
The full array has been operational since March 2012. Utilizing Enphase’s fairly comprehensive data tracking, I compared Arbor Terrace’s energy performance to similar properties that we own. While in the throes of summer heat — from mid-June to mid-July, a third of the days reached 101 ̊F to 108 ̊F (38 ̊C to 42 ̊C) — I expected to see daily peak consumption demand to be 125 to 140 kW without solar, peaking roughly between 4:00 p.m. and 6:00 p.m. The solar array produced 30 to 50 kW during this same time frame so I expected to see 25 to 35 percent reduction in peak demand.
Though we do not have a full consumption demand profile of the building, the billed peak demand showed a 40 to 42 percent reduction. I attribute the remaining peak reduction to the conservation measures we implemented during rehab construction.
Again, based on comparative data, I expected to see the solar array providing 20 to 25 percent of the building’s total kilowatt-hour consumption at this same time of year. The data show an effective 30 to 32 percent reduction. Again, I attribute the difference to the work on the building.
The bottom-line mission of any work we do on a newly acquired property is to develop a building that supports the well-being of the residents and staff. In addition to providing an emblematic statement of one of our core values, pursuing increased efficiencies translates to actual dollars saved — by Foundation Communities and by our residents — which then get re-invested in the programs, infrastructure and on-site support services that enable us to create housing where families and individuals succeed.
Based on the data to date, the solar and utility conservation work will result in roughly $35,000 per year that can be reinvested in the Arbor Terrace community.
For the last six years, as the design and development director, Sunshine Mathon has facilitated the deeply green design and construction of new multifamily properties for Foundation Communities, a nonprofit affordable housing developer with more than 17 communities in central Texas. Mathon holds a bachelor’s in physics and a master’s in architecture from the University of Texas at Austin. He is a LEED for Homes AP.