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Case Study

California Retrofit Measures Cut Energy Use by 45%

Location:Fair Oaks, CA

A foreclosed ranch home gets air-sealing work, insulation upgrades, a solar hot water system, and a PV array

With help from the local utility, a California builder has turned a foreclosed property into a cutting-edge energy-efficient demonstration home. The Sacramento Municipal Utility District (SMUD), the sixth-largest public utility in the U.S., has been working with builders and homeowners to construct energy-efficient homes for many years. SMUD recently partnered with the National Renewable Energy Laboratory (NREL) on this Energy Efficient Remodel Demonstration program.

The builder was Jim Bayless of GreenBuilt, who worked with SMUD and NREL to update a foreclosed ranch house with a wide rang of energy-efficiency and renewable-energy improvements.

“What we are trying to accomplish here is to demonstrate to remodeling contractors and to the public that you can achieve big energy savings and big bill savings whenever you do your next remodeling project,” said Mike Keesee, SMUD project manager. SMUD is hoping that such projects will show that remodeling should be more than just cosmetic. SMUD has arranged to lease the home for one year (September 2009 to 2010) as a showcase for energy-saving possibilities.

A Simple Plan

Together, SMUD and NREL set a simple design goal for the Bayless remodeling project: Reduce the existing home’s total energy use, both electric and gas (space conditioning, hot water, lighting, appliances, and plug loads), by at least 50 percent.

The team collaborated closely, using a whole-house (or systems) approach to integrate all household systems affecting energy use. The home incorporates a photovoltaic array and a solar water-heating system to help achieve the 50% energy reduction goal.

Whole-house upgrade

The Bayless home, a single-story, 1980s-vintage ranch, presented a number of challenges to the team, including large windows and all-electric heating, cooling, and water heating systems. The design team concluded that in order to meet the ambitious 50-percent energy reduction goal, they would need to air-seal the enclosure, upgrade the attic insulation, and replace the existing windows, HVAC system, water heater, incandescent lighting fixtures, and appliances.

NREL provided a detailed energy analysis using BEopt, a computer-based energy-simulation tool. BEopt evaluates a broad range of energy efficiency measures to determine the least-cost balance between energy efficiency and renewable energy measures.

The BEopt simulation showed upwards of 60% energy savings for the selected package of improvements. Based on current energy prices and anticipated future utility rate increases, the remodeled home’s annual electric bill is estimated to be $980, a savings of $2,151 per year or $179 per month.

A HERS rater performed a home energy rating that included an inspection of the attic insulation and blower-door and duct-tightness tests. The home exceeded the energy performance of a new home built to the State of California’s 2005 energy code (Title 24) by 22 percent. The home’s pre-remodel HERS score of 181.5 was improved by 103.6 points, ending up at 77.9.

Many happy returns

SMUD and NREL have predicted that the final package of improvements will reduce the home’s energy loads by 45%; these savings, combined with the energy production of the 2.3-KW photovoltaic array, are expected to yield a net energy use of about 10,000 kWh per year, a reduction of 58% compared with the estimated pre-retrofit electric consumption of about 25,000 kWh per year. An additional and important benefit, from SMUD’s perspective, is that the west-facing PV array will substantially reduce the home’s peak electric demand.

Working with SMUD and NREL on the project offered publicity for GreenBuilt as well as for subcontractors and suppliers. “I think that this model is a great opportunity for people to see, to touch and feel, what some of those [energy improvement] possibilities are,” said Jim Bayless, co-owner of GreenBuilt..

“We want to show the remodeling industry that this is something that they should consider. It’s more than just granite countertops and cabinets. It should also be a way for homeowners to gain a return on their investment,” said Mike Keesee.

Lessons Learned

Siding was removed from the home’s west wall, creating the opportunity to reinsulate it with blown cellulose. However, getting enough material into the wall to avoid settling proved difficult without overfilling, which created problems for installing the new siding. The drywall installer also had to remove some insulation in order to hang the drywall.

It was a challenge to find qualified, green-oriented subcontractors for certain trades, particularly air sealing and insulation.

Even though the house was built to California Title 24 energy standards, including R-13 batt insulation, the lack of air sealing and poor quality of the installation was evident when the home’s siding was pulled back. Significant air leakage was encountered along the floor plate, where the plywood siding tended to separate from the sill plate. Air infiltration staining was found on the wall insulation, and weeds were growing up into the wall. This condition, which also provided easy access for pests, was not easy to see and was difficult to fix effectively. The solution was to pull off all the siding on the west wall, remove the insulation, air seal all penetrations, joints, and seams (e.g., where the eave meets the wall), and insulate the wall with blown-in netted cellulose.

General Specs and Team

Location:Fair Oaks, CA

Bedrooms: 3

Bathrooms: 2
Living Space: 1748 sqf
Cost: $81/sqf
Year Built: 1980s; remodeled 2009
Designer/Builder: Jim Bayless, Phil Barnes & Scott Blunk, GreenBuilt Construction
Project Manager: Mike Keesee, Sacramento Municipal Utility District (SMUD)
Energy Analysis: Ren Anderson, National Renewable Energy Laboratory (NREL)

Construction

Foundation:Slab-on-grade
Walls: Existing east, north, and south walls (2x4, 16-in. 0.C., R-11) were not modified; west wall rebuilt with R-15 blown-in cellulose insulation
Roof: Asphalt shingles over radiant-barrier roof sheathing
Attic:Air-sealed and insulated with R-42 blown-in cellulose; kneewalls insulated with foil-faced 1-in. rigid foam (R-6) over R-15 batts
Windows: Vinyl windows with low-e argon-filled glazing(U-0.28 to U-0.29; SHGC 0.19 to 0.22). Velux Sun Tunnel (U-0.42, SHGC 0.40) in interior bathrooms; Solair Pro rectractable awning on west-facing sliding glass doors; Tucson SunFix automatic shades on west windows
HVAC: Goodman 16 SEER-9.75 HSPF heat pump w/ R-6 insulated ducts, tested to 4.5% leakage @ 25 Pa; programmable communicating thermostat; AirScape two-speed whole-house fan; Energy Star ceiling fans
Domestic hot water: 97 EF electric storage tank w/ Air Tap heat-pump "booster" retrofit with 2.11 coefficient of performance (COP), and 40-gal. integrated solar water collector (50% solar fraction)
Lighting:Replaced all incandescent lighting fixtures with Energy Star CFLs and Halo LED fixtures (master bath)

Energy

PV system: 2.3 kW; measured PV production, August 2009 to February 2010: 1,483 kWh, with 988 kWh exported to grid.

Solar hot water system: is supplemented by 2 electric water heaters (electric resistance plus air-source heat pump)

Annual energy savings:Estimated $2,151/year, $179/month (69%)

Appliances

*Replaced refrigerator with Tier 2 Energy Star (25% better than federal appliance standards) and dishwasher with Tier 2 Energy Star (.69 energy factor, 50% better than federal appliance standards);

*Control 4 Home Area Network controls HVAC and lights, monitors home’s energy use and solar PV electricity production w/green switch.

*Refrigerator and range are Energy-Management-Enabled for future "smart grid" interaction.

*Home is an NREL "laboratory house," being used to monitor performance of the heat pump water heater, solar water system, and other energy systems and to conduct experiments, including a precooling experiment during summer 2010.


  • Water Efficiency
  • Dual-flush toilets (1.28 gpf average)
  • Native, non-invasive, drought-tolerant plants
  • Reduced turf area
  • Automated irrigation
  • Water-saving showerheads and faucets
  • Water-saving showerheads and faucets
  • Indoor Air Quality
  • No fireplace
  • No-VOC paint
  • All-electric home
  • Air King Energy Star—rated range hood and bathroom exhaust fans on timers
  • Air sealing complies with Energy Star's Thermal Bypass checklist
  • Blower-door test: Pre-retrofit: 6,830 cfm, 26 ACH @ 50 Pascals; Post-retrofit: 1,080 cfm, 4.1 ACH @ 50 Pascals; ACH (nat) = 0.21
  • Green Materials and Resource Efficiency
  • 100% recyclable nylon carpeting
  • Locally made ceramic tile flooring
  • No-VOC paint
  • Compost bin
  • Locally produced, no-added-formaldehyde cabinets
  • Recycled-content kitchen and bathroom countertops
  • Pallets, nursery plant containers, and paint buckets returned for reuse
  • Salvageable components and materials reconditioned and reused (tub and shower surrounds, selected doors, lumber and landscape materials)
  • Other salvageable items donated to Habitat for Humanity and Snowline Hospice
  • Demolition and construction waste sorted and recycled (aluminum, steel, wood, concrete, beverage containers, cardboard, and green landscaping waste)
  • Shade trees planted on southeast and south to avoid shading west-facing solar systems

Certification

LEED for Homes Platinum Rehab
HERS Rating = 63

Image Credits: Amy Levin

Content By GBA
  • USGBC
  • ASID