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TAH.MAH.LAH. Net Zero Residence

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When Paul Holland and Linda Yates set out to build the “greenest home in America” on the North California hillside, they envisioned something that would debunk the myths that green building was ugly, too expensive and alters your lifestyle. In response, Hill Glazer Architects and builder, MGM Construction worked together to create a “regenerative” building that adheres to four principles of sustainability – energy, materials, water and habitat.

Tah.Mah.Lah, as the house is called, is named for the Native American Ohlone word for puma or mountain lion. The main house has four bedrooms and baths and features large, open entertaining spaces with 24-foot high ceilings and huge 12-foot high sliding doors that open the home to the spectacular outdoor areas and mountain views during the day and star-studded night sky during the evenings. Other areas include a library, large playroom, open loft area, outdoor dining room and a master suite with a sauna and a steam room.

The LEED Platinum rated 5,600sft residence has been designed to be as simple, efficient and as environmentally friendly as possible. It incorporates green practices ranging from 27-kw, 120-panel solar array to power the house and geothermal system for heating and cooling to the FSC-certified wood, native stone, R-42 ceiling insulation and triple-glazed windows. Much of this super-green home revolves around energy conservation, from the passive solar siting of the home to the water conservation systems and to energy-saving electronics like super-efficient LED lighting, occupancy sensors, motorized window treatments and a home control system that’s operated almost exclusively from the owners’ iPads.

Design

In building a house like this, it’s important to design to reduce energy needs first, then look to offset the rest through alternative energies like solar. Designing the house with big windows and plenty of light allows both solar gain and the ability to never turn lights on until it is dark. The passive solar gain means almost no heat is required in the winter. Where heating and/or cooling is needed, it is provided by radiant slabs supplied by ground source heat pumps. Domestic hot water is also provided by the heat pumps. Ventilation is provided principally by operable windows. To allow for proper air flow during cooling periods, mechanical fans exhaust air at the ceiling level. All mechanical systems are electrically operated to allow for net-zero energy use in conjunction with a photovoltaic system on the roof.

Integrating building science for optimal airflow and efficiency is also very important. The siting of the home helped the water conservation systems as it gets the benefit of gravity for the flows of the black and graywater into the filtering system and subsurface irrigation and rainwater into the cistern. The graywater from showers and blackwater from toilets goes through the septic system then through subsurface irrigation to water the yard’s meadow of native grasses that use 80 percent to 88 percent less water.

Rainwater is collected in a 50,000-gallon cistern for re-use as well. Inside, hot water is produced by heat pumps tied to the underground geothermal heating system, which in turn uses pumps powered by the solar array. Even the distribution of the hot water is efficient. Four hot water recirculators deliver warm water to sinks without wasting cool water, which is voided back into the water tank for reheating.

Material

When construction ended in 2011, the net-zero-energy, zero-carbon emission spread earned the highest LEED rating for a custom residence of its stature. To make the home not only passive (little impact) but actually restorative (positive impact), it was built as a structure that “generates more energy than it uses, rebuilds habitat, saves and repurposes water, and reduces and reuses waste. Most of the materials were salvaged, including the recycled steel roof, reused limestone fireplaces, kitchen hood and hand railings swiped from a 102-year-old granary. The structure itself is made of cedar “harvested from woodlands certified according to guidelines of the Forest Stewardship Council,” while the wood floors were salvaged from old barns. What’s more, there is no paint, ducts, or fossil fuels. Heat comes from geothermal energy—a system pumps water deep underground, where it’s warmed by the Earth’s thermal energy before being pushed back up to heat the floorboards. The property also features a “sustainably built” pool, revitalized wetlands, and a willow-weed playhouse by Australian artist & and bonafide weed expert Patrick Dougherty. “

Technology

To monitor the water systems, owners can peek in on cistern levels via a web portal on their iPads. There are also apps for the in-floor heating, a weather station, the irrigation system, pool filtering and more. Most of the home’s everyday functions can be controlled via their iPads and iPhones, or from keypads used in place of typical lighting switches in each area. Lights can be dimmed, scenes can be set, security can be armed, ventilation adjusted and audio and video controlled all from mobile devices or keypads. A Control4 home control system ties most of these systems together, and is the finishing touch in this sustainable home. The control system automates the heat recovery ventilators (HRVs) that bring fresh air into the home, turning them on at different times, depending on the time of year and how much ventilation may be needed. In addition, occupancy sensors throughout the home turn lights off after 10 minutes of room vacancy. The system also operates motorized MechoShades allowing sun in to the interior spaces.

Tah.Mah.Lah. has been designed to represent an exciting summary of what building green can amount to. Special care was taken across every dimension of green building to have minimal environmental impact and maximum restorative effect, while providing an environment appropriate for the family and the broader community. The integrated delivery process included energy modeling of schematic design prior to design development, full budgeting of sustainable design technologies and strategies, and use of advanced tools such as daylighting simulation software and a heliodon for sun-angle and shading analyses. The design charrette addressed specialized aspects of the design to innovate and optimize solutions by engaging vendors during schematic and design development phases and making iterative review of materials sourcing, constructability and performance specifications.

Tah.Mah.Lah. is a legacy project intended for 100+ year life span. The design of the home and its systems anticipate evolving needs over time, with built-in flexibility for the current growing, changing family and future occupants. Off-grid capabilities and above-code structural design enable home to serve as a community shelter after a major seismic event.

 

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