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CLIENT:
The owners, both practicing Buddhists and avid modernists, were interested in creating a weekend retreat from Washington, DC in the Shenandoah Valley. The natural setting with distant views and nearby rock outcropping were maintained for enjoyment while meditating. The structure also doubles as a place to stay for family and friends. The clients’ conviction for energy efficiency and minimal waste or consumption in producing, delivering, installing, and maintaining materials and products inspired a sustainable project. The team of client and architect agreed on the importance of local craftsmanship in nurturing local culture — the other half of sustainability. The project, designed by Carter + Burton Architecture, is part of the LEED for Homes Pilot program and received Gold certification. Southface was the LEED for Homes provider for the project.+

DESIGN:
County restrictions on size for a Studio in Clarke County warranted a design which feels big for spaciousness, views and light while maximizing efficiency. An organic shape felt right which stretches out to take in as much southern light as possible while still being compact. This outbuilding fits with the site while maintaining a modern purity of form and space rarely seen in this rural setting. The structure’s circulation features doorways at each end. A beamed entrance to the east and the western end sits high with a deck on the view side feeling like a tree house. The walls and ceiling curve to provide an energy efficient and site responsive design which respects the allotted space requirements. The simplicity of the structure required an attention to detail and materials that are achieved with the customization of most elements in the project.

SITE:
The mountainside site proved challenging for design and construction. The chosen site rests behind a craggy stone ridge on a 5 acre lot an hour west of Washington DC. The placement of the Studio 100 feet functions and systems, reducing the overall impact on the site. The view from the road 70 feet below changes with the seasons as the two structures anchor the ends of the 100 foot long rock ledge.

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The native plants remain intact featuring Mountain Laurel, hardwoods, lichen covered boulders and over an acre of wild blueberries. Care was taken in the design of the landscape around the house to allow for the forest to return to its natural state as quickly as possible. Measures were taken during construction to protect the existing trees and control erosion, including covering the topsoil and using erosion fencing to prevent additional dirt from sliding down the steep hill. Permanent erosion measures include planting indigenous trees to absorb water in the meadow formed by the staging area of construction, and a low retaining wall which scoops out of the hill to form the grill area and front terrace.

The driveway does not extend beyond the Main House – visitors walk downhill to the Yoga Studio. The living roof from Building Logics featuring sedums and a maintenance free system for a low pitched structure saves 30-40% on energy bills while retaining 70% of rain water to aid with latent cooling and storm water management on the site. The minimal landscaping – indigenous trees and succulents on the living roof are non-invasive and drought tolerant plants, which also saves in maintenance and water consumption on the site.

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SYSTEMS:
A geoexchange system provides efficient space heating and cooling and all of the Studio’s hot water needs. The system consists of a ground-coupled heat transfer loop (geoexchanger) connected to a liquid-to-liquid heat pump and a liquid-to-air heat pump. The loop employs vertical and horizontal ground tubing runs, and is sized to heat and cool both the Studio and the Main House.

Heat pumps are limited in their ability to raise and maintain temperature in domestic hot water storage tanks. The mechanical engineer was concerned this risks growth of biological organisms in the tank. For this reason, a thermal storage system (TSS) using an aqueous heat transfer media (HTM) was employed. When a faucet or shower is turned on, cold well water draws heat from the TSS via a parallel-plate heat exchanger.

 

This arrangement allows for continuous heating of the incoming water stream without worry regarding an immediate drop in water temperature, as is the case with traditional domestic hot water storage tanks when the hot water runs out. The HTM is heated primarily by the liquid-to-liquid heat pump. A mixing panel, coupled to the TSS, circulates tempered HTM through a plastic tubing loop embedded in the concrete entry and bathroom floors. This assures year-round comfort for bare feet on these floors.

The liquid-to-air heat pump provides space heating and cooling via a forced-air system. A heat recovery ventilator (HRV), along with high-purity air filtration ensures indoor air is kept exceptionally clean. When the liquid-to-air heat pump is operating, a desuperheater contained within the unit rejects heat to the HTM. This tops off the overall temperature of the TSS without needing to operate the liquid-to-liquid heat pump. The reduced number of cycles reduces the overall energy consumption and prolongs the life of the equipment. An equally important aspect of the desuperheater function is due to the fact that the heat rejected is essentially “free” during cooling operation. This is because the heat from the building that is normally transferred to the ground is instead transferred to the TSS for later use.

The Main House and Studio are a second home for the owners. To minimize energy use while the Studio is unoccupied, the TSS is shut down and the space heating/cooling system maintains an “offset” temperature. The owners can remotely switch the systems to occupied mode, so space temperature will be comfortable and the TSS will be able to meet domestic hot water needs when they arrive.

MATERIALS:
This project tested the limits of construction technologies for the area and its tradesmen. The following items created unique spaces, details and functional attributes:

The design team considered S.I.P.S. for many reasons including structural strength with less material, high R-value, low air infiltration, and use of recycled materials in the OSB and expanded polystyrene bead foam. After a tour of the local SIPs factory only 23 miles away where they were showing a curved panel sample that another designer wanted to use to build a boat, the designer knew that curved panels were possible. The news that SIPs could provide a clear span of 17 feet over an entire space rather than be interrupted by rafters (more savings of wood resources) lead to the idea of curved roof panels. All these factors helped to pilot a unique design strategy for the Yoga Studio, where the client can now lead others in yogic practices in a material and energy efficient space.

The project also employed many environmentally preferable products, as recommended by LEED, to satisfy the clients’ desire for a “healthy” interior environment and sustainable materials. These materials include:

• Poplar boards from a sawmill 3 miles away were used to board-form the concrete foundation walls. Soy oil was used as a natural release agent before the boards were air dried and planed for reuse as flooring and curved wall panels inside the Studio. These boards have a richness of pattern that serves as art work for the structure while also rooting the project to this place.

• No VOC-laden carpet or paint was used in the house. As an alternative to gypsum wallboard and paint, a technique of beeswax/resin mix on canvas pulled over MedEx MDF (no added formaldehyde to the medium density fiberboard) was used and installed by a local craftsman.

• Stainless steel ceiling panels were used indoors and on the porch ceilings for indirect reflected lighting and an airy feel. Maintenance-free galvanized corrugated metal siding creates a rural outbuilding feel, which some may argue has a terrestrial quality as the moon usually rises from behind the structure.

• Colored glass tile lines the bathroom walls and ceiling while a radiant terrazzo ground concrete floor with cast in place floor lights covers the bathroom and entry hall areas which creates a larger feel.

• Custom steel handrail at the loft with resin and grass panels serves dual purpose as safety feature and an art element.

• A custom steel and wood ship’s ladder saves space while allowing natural light to blend to all corners under the loft.

• Custom wood windows were fabricated 10 miles from the site by the builder and are low-e with a solar heat gain coefficient high enough to allow for some of the sun’s heat to be absorbed by the building as a passive solar technique in the wintertime. This is offset by custom stainless shading louvers which allow for a curtain free approach to passive solar light control in the summer, blocking the sun’s rays from over-heating the space.

• Built-in floor berths are detailed for storage or possibly future sleeping bunks on special occasions when the weekend camping trips are interrupted by severe weather or unwanted intruders like the local family of black bear often seen on the property.

• An outdoor built in concrete grill and bench forms a retaining wall for steps while relating to the concrete carport near the Main House. TXactive concrete (the first pour in North America) features a pollution abatement system using photo catalytic cement.

CULTURE:
The simplicity of the diminutive structure required more attention to detail and materials to maximize the perception of a large space. This was achieved with the customization of most elements in the project. Both the client and the designer value the work of local craftspeople to support the local trades and economy, as well as ensure a heightened level of care and craft in the resulting product. The designer, the client and the builder met on a weekly basis to discuss design issues that needed to be resolved that week.

There are some key features that are worth highlighting about the project:

• After using the 22” wide poplar boards from a sawmill 3 miles away for formwork of the foundation, the builder and his team planed the wood for use inside the house as flooring and wall panels.

• The builder and his team spent weeks in his shop constructing all the wood windows and doors.

• The doors have custom steel handles sized to be comfortable for a hand grip with a narrow profile for the tight spaces.

• Another key feature of the Studio is that it doubles as a bunkhouse. There are beds built into the floor diaphragm with trap doors hiding them during the day. Bunk beds built out of a steel frame with custom mattresses are located in the loft space. With all these beds in use, the Studio can sleep nine people in a minimal amount of space if needed on special occasions.

• A custom steel and wood ship’s ladder saves floor space while allowing natural light to blend to all corners and doubles as access the loft and as a sculptural piece for the Studio space.

• All the cabinetry in the Studio, including a wash closet, a shoe storage bench by the front door, bathroom wash basin cabinet, kitchen cabinetry, and a bench and cabinet at the grill center was built by local craftspeople.

 

• Materials which are rooted to the region, such as the maintenance free galvanized corrugated metal siding creates a rural outbuilding feel. The grain of the wood extracted from the region is left exposed inside the Studio highlighting the sense of place.

• All the subcontractors working on the site, including the mechanical contractor, the security contractor, and the electricians were from within 30 miles of the site. The benefits of utilizing local craftspeople as well as experimenting with and using environmentally responsible materials in inventive ways reinforces sustainable concepts and creates and enduring sense of place.

Project Details:
Location: Clarke County, Virginia – USA
Architects: Carter + Burton Architecture – www.carterburton.com
Date: 2007
Certifications: LEED Gold certification – LEED for Homes Pilot Program

Hat tip to Architecture Lab