Guesthouse and Art Museum near Sydney

In the guesthouse of Bundanon, a three hour drive south of Sydney, the wonders of art and nature are close together. Towards the east, views are directed to Shoalhaven River below. A nature park is situated westward. And only a few steps separate the entrance to the hotel from Bundanon Art Museum, both created at the same time. The latter houses the works of Australian painter Arthur Boyd (1920 - 99). The state-owned foundation that manages Boyd's legacy is also the client for whom Kerstin Thompson Architects created the new structures. The building volumes could not be any more different from each other: one is a museum made of exposed concrete and largely set below grade, while the other is a steel bridge that comprises the guesthouse, 165 m long and 9 m wide, reaching far into the landscape. Flood protection, fire protection and barrier free access were essential factors that influenced the design. In addition, the new structures were not supposed to compete with the Boyd Education Center, built by Glenn Murcutt, Reg Lark and Wendy Lewin in 1999, farther towards the south of the site. Raised 23 m above the river, the ground floor of the guesthouse is considered flood proof and matches the museum entrance level. The bridge spans across a valley basin. When strong precipitation occurs, large quantities of water flow through it towards Shoalhaven. The building was also required to maintain a distance to the nature park and the bushfire hazard originating from it. The steel structure with dark painted finish is inspired by historic trestle bridges that, in earlier days, served to raise railway lines above flood plains in Australia and the USA.

For a long time, Bundanon was Boyd's residence. His former garage is now the hotel reception building. At the foot of the bridge, a café serves to welcome the hotel guests and museum visitors. Behind it, a multi-purpose room can be used for events and workshops. The longitudinal guestroom tract is structured by multiple "breakout zones" that create recognisable spatial intervals and comprise covered areas for lounging, open to both sides. Inspired by Boyd's love of plein air painting, the architects designed the guestrooms and bathrooms as the only closed spaces within the guesthouse. The corridors are exposed to the outdoor climate. The bridge skeleton continues in front of the facades and supports a striking corrugated sheet metal roof that covers the hotel rooms without touching them. The latter received dark sheet metal siding on the exterior and dark glazed eucalypt wood panelling facing the corridors. On the interior, walls are clad in eucalypt plywood panels of lighter colours. Each room features one window with fixed glazing and a ventilation element consisting of wood slats. Windows can be darkened by use of sliding shutters made of corrugated sheet metal that also cover the ventilation openings and protect them from ember attacks in the case of a fire. JS

The art museum and the guesthouse combine three planning goals: minimise resources consumption and CO2 emissions, offer protection from fire and flood hazards, enable self-sufficiency as far as possible in terms of energy and water supply. The latter was necessary since Bundanon is neither connected to a potable water network nor a sewage system. Further, voltage drops in the power grid occur often here.

A precondition for being self-sufficient as far as possible is the efficient use of energy and water. The local climate is beneficial to this purpose: Bundanon is located in a warm temperate zone. Temperatures are mild throughout the year, with the exception of periodic hot spells in summer and cold winter nights.

A bulding with multiple climate zones

The zero energy concept limits air conditioning in the guesthouse as far as possible. Thermal modelling showed that the building can offer its users optimal climate comfort without large storage mass. Only the café and the large community room feature window ventilation and air conditioning. In the guestrooms, ventilation, temperature and daylight intake can be controlled by hand. Guests themselves are responsible for their comfort levels. Air intake occurs through manually controlled wood slats in the guestroom facades. Air is vented into the corridors through a manually operated flap above each guestroom entrance. Summertime cooling is provided only by ceiling fans and heat is supplied by small electrical radiators. They were also installed in the open loggias and are intended to ensure pleasant temperatures during winter. The required power is generated by a 100 kW photovoltaic unit on the roof above the guestroom tract. A 100 kWh battery is located on the basement level of the guesthouse.

Stable indoor climate conditions are necessary to greater degrees in the underground museum building. However, variations are possible even here: Tolerances for temperature, humidity and daylight intake in the exhibition halls are more restrictive than in the entrance area or the sanitary spaces. The placement of the building below grade and its solid reinforced concrete construction type provide it with enormous thermal stability. As a result, energy demands for the heat pump system with 190 kW yield, used to heat and cool the building, are reduced. The system is connected to 27 geothermal probes, reaching 100 m deep. According to Paul Stoller, director of the environmental design consultancy Atelier Ten, this solution was more cost-efficient and resilient to bushfire than gas heaters, mechanical refrigeration and cooling towers on the exterior.

The new building complex receives potable water exclusively through rainwater harvesting and an on-site well. Water is led into a purification system on the basement level of the guesthouse, where it is treated and directed to the café and the guestrooms. Grey water and sewage are routed into a small, on-site wastewater treatment plant. The treated water is later used for watering the landscape.