Mass market builder Pulte developing zero net energy home prototype
Photos courtesy of PulteGroup Inc.
To prepare to meet tough building codes, PulteGroup Inc. is producing a zero net energy (ZNE) home prototype in Northern California.
Pulte says it is the largest builder to participate in a pilot aimed at building new homes to achieve maximum energy efficiency and utility grid load reduction.
“The Pulte ZNE prototype will help guide and create best practices for the Company in building more energy efficient new homes in California and, ultimately, across the nation,” said Ryan Marshall, president of PulteGroup. “Our goal for this prototype is to help define the most efficient path to building zero net energy homes that effectively balance constructability, cost and quality.”
The Pulte ZNE home prototype embraces California’s long-term zero net energy goals by leveraging advanced design, construction and on-site renewable energy solutions. The home’s design combines near airtight building methods, highly efficient insulation, HVAC, lighting technologies and more, with on-site solar energy production to offset the home’s energy consumption.
Pulte is participating in Pacific Gas and Electric Company’s (PG&E) Zero Net Energy Production Builder Demonstration program that supports California’s energy efficiency and climate goals for all new residential construction to be zero net energy by 2020.
“California is clearly leading the charge on zero net energy, and we believe this is an opportunity to harness the lessons learned with our building partners so we can offer consumers the ultimate combination of affordability, quality and energy efficiency in the future,” Marshall said. “We are already developing plans for future Net Zero prototypes.”
A ZNE home or building is one designed with the goal of producing as much energy as it uses during a year. To cope with fluctuations in demand, ZNE homes are typically connected to the grid, exporting electricity when there is a surplus, and drawing electricity when not enough is being produced. Construction of the prototype in Botanica by Pulte Homes in Brentwood is expected to be complete in May 2016. The energy performance of the home will be monitored for a year after it is sold, and overall energy performance and consumption will be evaluated.
The ZNE project is a collaboration with many key partners, including solar power provider SolarCity, building materials producer Owens Corning, and heating/cooling systems provider, Lennox. “These companies are committed to offering the most innovative, renewable and affordable solutions that improve the lives of Pulte homebuyers and the world we live in,” Marshall said.
Pulte ZNE Home Prototype Features
A tighter building envelope reduces the amount of air transfer between indoors and outdoors. The prototype includes a building envelope design that provides high thermal performance and long-term durability, while also reducing material use (and waste). Sealing the home envelope to minimize air leakage is a key component of the Pulte prototype. Air leakage will improve (be reduced) by approximately 30 percent - going from 5 to 3.5 ACH50.
The Home Energy Rating System (HERS) Index is a standard by which a home's energy efficiency is measured, developed by the Residential Energy Services Network (RESNET). A HERS score is used to help compare the energy efficiency of a Pulte home to both a typical existing home and a typical new home. Pulte retains certified independent HERS energy raters to provide energy efficiency ratings for homes as designed. The targeted HERS rating for the Pulte prototype is Zero. The lower the home's HERS score, the more energy efficient it is.
One of the most influential components of achieving a zero net target in the prototype is the process of insulating at the roof deck of the home, versus the ceiling line. Insulating the prototype home at the roof deck keeps the attic significantly cooler. Box netting is used to suspend insulation at the roofline. Because the attic becomes conditioned space, roof and attic vents are eliminated and heating and cooling loads are reduced on the HVAC.
Fresh air is introduced 24/7 in the prototype via a continuous-running exhaust fan in the laundry room, plus the introduction of fresh air from an outside air duct that is detected through automatic sensors. Even though the fan runs at all times, the system is so efficient that it provides higher than normal quality of indoor air and still saves electricity. To help remove contaminants from indoor air, the prototype includes a high-end air filtration system with a 5-inch thick, pleated, MERV 16 filter, which is equivalent to a medical-grade filter that removes much smaller particles from the air.
The prototype has a Lennox high efficiency, SEER 19, multi-speed heating and air conditioning system. The Lennox heat pump is being used instead of a gas furnace, to transfer the air conditioning load to 100 percent electric, which also results in zero VOCs released into the environment. The home includes Wi-Fi-based “smart” thermostats that control fresh air induction and provides more control and convenience with remote capabilities.
This prototype takes the tankless hot water heater to the next level with a high efficiency integrated, on-demand Rinnai recirculation pump that eliminates water waste. Tankless water heaters heat water on demand as opposed to traditional storage-type water heaters. In addition to a sensitive flow switch that detects demand for hot water, the prototype also incorporates an integral hot water recirculation pump that charges a dedicated and insulated hot water loop with hot water, reducing the volume of water wasted at each fixture while waiting for hot water to arrive. A wireless switch is provided at the kitchen sink and in the master bathroom that initializes the pump, which runs until a water temperature sensor detects an increase of approximately seven degrees. The sensor then shuts the pump off.
VOCs will be significantly reduced or eliminated in the prototype home with the use of a heat pump that provides combustion-free heating and cooling, no-VOC paint, laminate and tile flooring creating increased indoor air quality. VOCs are Volatile Organic Chemicals in some products such as paint and flooring.
Even though the prototype home is significantly more energy efficient than a traditional home, an important feature is energy production.Pulte is partnering with SolarCity, the nation’s leading solar power provider, to equip the prototype home with a next generation solar system: an estimated 14-panel, 4.34 kilowatt solar array. According to SolarCity, the state of the art solar panels expected to be utilized for the system are SolarCity’s high-efficiency rooftop solar panels that will be made in the United States. Homeowners will see the benefits of these panels in two ways:
The high-efficiency design allows for more power production from a single solar panel, making it possible for SolarCity to install a solar power system that doesn’t take up as much roof space as a traditional design might, but still provides all the power a home needs.
The solar panels are designed to be aesthetically pleasing for homeowners. The sleek, black panel design combined with SolarCity’s proprietary mounting system work together to create a solar system that integrates seamlessly with the home’s current roofline and aesthetics.
To keep the prototype cooler and use less electricity, LED can lights will be installed in all locations; and decorative LED fixtures will be included in areas such as bathroom vanities, kitchen, under cabinet lighting, and coach lights. LEDs (Light Emitting Diodes) generate little heat, consume a fraction of the electricity of traditional lighting (which is beneficial for the cooling loads for the HVAC system in the summer), are higher efficiency, and have a life span dramatically longer than incandescent and fluorescent lamps.
The prototype home will include a Site Sage monitoring system that will track the actual use of switches, outlets, major appliances and lighting in the home. The real-time readings will monitor how many kilowatt-hours are used and allow specific use to be monitored and evaluated. This system helps lower electric bills by providing automatic cost, and usage and appliance performance feedback by monitoring up to 24 individual circuits including the two mains.
- Low-e coatings on vinyl windows to reduce energy loss by as much as 30% to 50% compared to regular windows. (Also provide up to 95 percent UV ray blockage).
- An enhanced load and breaker configuration has been designed to monitor separate loads and circuits. Tracking specific locations will assist in identifying unusual use and help influence future designs.
- Energy efficient, Energy Star rated appliances (cabinet-depth refrigerator that includes a feature that turns on an energy saving mode if not opened for 24 hours), induction cooktop, and gas front-loading dryer.
- Low water use fixtures and appliances.
Pulte ZNE Prototype Kitchen Innovations
Pulte conducts extensive consumer research to identify what matters most to homeowners and has optimized kitchen designs just as it has with floorplans overall.
Pulte kitchens are designed with a comprehensive lighting plan that creates multiple sources of natural light, task lighting and decorative light. Also important to the kitchen is the design of “smart zones” that maximize flow for storage, prep, cooking and clean up.
Some of the kitchen innovation designs in the prototype include:
- Electric induction cooktop that is more energy efficient, provides cooking precision, faster heating, easy-to-clean surface, with a sleek modern look that keeps the kitchen cooler.
- Under cabinet LED lighting that illuminates tasks and creates a beautiful look.
- Whirlpool Energy Star appliances certified by the Department of Energy that use 10 to 50 percent less energy and water than standard models. With appliances and lighting often accounting for more than one-third of an average homeowner’s utility bill, incorporating energy efficient appliances can translate into significant savings.
- Lower cabinets with deep pull-out drawers that are more useful.
- Counter-depth refrigerator that provides a streamlined look, more storage solutions, convenient access to contents, automatic system that creates ideal temperature for food, and better traffic flow by not protruding in congested areas.
- Easy storage solutions such as two-bin trash and recycling containers.
Making the most important room in the house innovative also includes the selection of design finishes that are timeless, contemporary and inviting. The prototype kitchen interior includes warm, contemporary undertones with design features such as: white shaker cabinets and grey floors, taupe countertops and subway backsplash.
Zero Net Energy Partners
From the time the California Public Utilities Commission adopted the goal for all residential construction in the state to achieve zero net energy by 2020, Pulte began discussions with its trade partners to prepare for the transition.
Pulte will work collaboratively to identify improvements and enhancements in energy efficiency that can be applied to future Pulte ZNE prototypes and new homes that will ultimately be offered to homebuyers. The Company is already discussing plans for a second ZNE Prototype.
With the state of California in the forefront of energy efficiency initiatives, Pulte is participating in PG&E’s Zero Net Energy Production Builder Demonstration in support of the state’s long-term energy goals.
Through this program, PG&E collaborates with builders to provide design consultation and energy performance monitoring for the development of ZNE homes. Once construction is complete and a homebuyer purchases the home, PG&E will track the ongoing energy performance of the home for a year to evaluate overall energy performance and consumption to determine that the home is performing as designed.
Pulte is collaborating with SolarCity, the nation’s leading solar power provider, to supply affordable solar power to the home. SolarCity is expected to install a 4.34 kilowatt solar power system at the prototype home. The solar system will be monitored 24/7 and SolarCity will handle everything in the solar process from financing and installation to monitoring and maintenance. The companies also currently work together to install solar power on Pulte communities in California and Arizona.
The Owens Corning ProPink High Performance Conditioned Attic system in the prototype is the smart way to optimize home comfort, durability and value per square foot. The system air seals and insulates the attic space for maximum efficiency, creating a buffer zone between the roofline and livable space of the home, resulting in lower monthly heating and cooling bills*, improved home comfort and a higher standard of living for homeowners. (*Savings vary.)
Other partners involved in this innovative pilot program include: Alameda Electrical Distributors); BIRAenergy (modeling and technical analysis); Blue Mountain Construction Services (HVAC); BMC West (framing); Budget Electric; BZ Plumbing; California Living & Energy (HERS rater); Davis Energy Group (energy consulting/monitoring) Lennox (HVAC equipment); Leviton Manufacturing Co. (electrical systems); OJ Insulation - Installed Building Products; Owens Corning (insulation products); Resource Refocus LLC (ZNE consulting); Rinnai (tankless water heater); Seagull Lighting (Zurier); Site Sage; SolarCity; Whirlpool (Energy Star appliances); and more.
Read more about building green homes.
Topics: Appliances, Building Green, Certification / LEED, Connected Homes / Smart Homes, Energy Recovery & Heat Recovery, Energy Star, Going Green, GREAT GREEN HOMES, Heating & Cooling, Home Design & Plans, Indoor Air Quality, Insulation, Kitchen, Lighting, Solar Power, Sustainable Communities, Thermal Envelope, Water Saving Devices, WaterSense