Gaia Napa Valley Hotel

This hotel near Napa Valley is designed to appeal to eco-tourists. The design is based on a courtyard to create an oasis in the relatively hot climate, turning inwards to an artificial lagoon and swimming pool. Most of the 140 guest rooms are raised on a second-floor plinth and accessed via a double-loaded, clerestory-lit corridor. Public areas such as lobby, restaurant, and conference rooms occupy much of the ground floor, in addition to service-oriented spaces such as the kitchen, laundry, and staff offices.

The hotel developer established a strong environmental imperative from the project's genesis. The design team was assembled with the understanding that the project would emphasize the symbiosis of human and natural relationships. Architects, engineers, and consultants with expertise in permaculture, water management, recycled and sustainable materials, alternative energy sources, passive solar design, energy efficiency, thermal comfort and daylighting were invited to collaborate in the project. Currently the developers have their sights on achieving a LEED Platinum rating.

We have consulted on a wide range of issues including: climate analysis, building envelope, material assemblies, daylighting and shading, conditioning systems, material specification, alternative energy sources, and energy efficiency. We are responsible for sizing, specifying and coordinating the design and economics of the significant photovoltaic array as well as for the LEED certification process. All of the consulting has been closely coordinated with the architect, landscape architect, engineers, and other consultants.

The climate at American Canyon is prone to long periods of high temperatures so keeping hotel guests cool is a challenge. The building envelope is well-insulated and window apertures effectively shaded, particularly to the west and south. A green roof is designed to provide additional insulation, shading, and evaporative cooling. Windows are specified to incorporate spectrally selective glass with low U-values and shading coefficients. Interior partitions consist of two layers of sheetrock for increased thermal mass and acoustic isolation. Finally, the concrete floor slab will be cooled by night ventilation supplemented by an in-floor chilled hydronic system.

During cool times of the year, the hotel will be passively heated by direct solar radiation. The high thermal mass of the floor and partitions will absorb some of this heat and re-radiate it during the evening. On overcast, or cold days, active thermal conditioning will be supplied by radiant hydronic heating embedded in the floor slab. In addition to this system's energy efficiency, it is particularly appropriate for a hotel because it provides the highest degree of occupant comfort while producing minimal noise.

Daylighting and shading was another area of concern, as we sought to maximize visual comfort while minimizing the use of electric lighting. In the double-loaded corridors this was achieved by introducing a continuous clerestory that wraps around all four wings of the hotel. The guest rooms, which are side-lit, use high performance glass to reduce contrast between outside and inside. Vine-covered trellises shade the clerestory to modulate views of the bright sky and protect the rooms from excess solar radiation. Effective daylighting is coupled with various strategies to reduce electric loads, including key-slot activated lighting controls and reduced number of electrical lights and outlets.

Other measures include solar electric and solar hot water. Panels are sized and priced based on calculated electrical and hot water demands. We have also coordinated the selection of alternative energy sources based on state tax credits, incentives, and power company buy-back options.

An interesting aspect of this project has been working with the client to coordinate the energy efficient and ecologically responsive aspects of the design with the unique experiential qualities of a resort hotel environment. Imagining a guest's perspective in the eco-hotel, we have helped the design to emphasize sensual elements which also play an environmental role, such as the smell of vines on trellises, the sound of chirping birds on the green roof, and the cool comfort of a concrete floor and cool walls on a hot summer day.