Ecohouse Bariloche

• Limited site location • Thermal insulation • Greenhouse and rock store integrated into design • Roof integrated photovoltaic system • DHWS • Wastewater reuse for irrigation

The Fuentes-Lopez house is located in Bariloche, an important tourist and ski centre in the cold southwest region of Argentina. The house is built in a low-density, hilly and wooded area, approximately 18 km from the town centre, with attractive views of surrounding mountains and the Nahuel Huapi National Park. Planned for convenient and flexible family living with four children, the house also provides a study and home office for the parents. The large kitchen-living-dining room forms the centre of family life. The main bedrooms are located on the ground floor. The upper floor was originally planned as a large flexible open space with possibilities for later subdivision to form additional bedrooms. The clients, with their

Ecohouse Bariloche

children, were actively involved in all stages of the design process including programme formulation, location, design alternatives, detailing and construction.

ECOFEATURES EXPLAINED Limited site location form

Local regulations that only allow limited tree felling impacted the design stage. Other 'setback' regulations and site characteristics limit the possibilities for locating vehicular access and siting for good solar access. The location of the house was carefully chosen to take advantage of an existing clearing in the woods and a reasonably level area, although difference of 2 m in height within the 'footprint' of the building still exists. A heliodon (a device that simulates solar angles and measures the number of hours of potential sunshine) was used to select and define a suitable area and to detect those trees that reduced solar exposure in winter. A reasonably clear view of the sky is achieved in orientations between 45° to the east of north to 45° west of north, with maximum obstruction height of 26° to the north (note that the house is located in the southern hemisphere and receives winter sun from the north), falling to 19° to the northeast and northwest. The form combines a compact overall shape to reduce heat losses with a good exposure to the north. This is achieved by superimposing a V shape, with the principal internal sides facing northeast and northwest, on a rectangle with the longer side facing directly north.

Thermal insulation

The volumetric heat loss coefficient of the house is under 0.8 Wm-3 K, considerably less than the maximum value of 1.4Wm-3 K recommended for a house of this size in Bariloche (National Standards for Thermal Insulation). These low heat losses are a result of the compact form and very low thermal transmittance of both walls and roof. About 40 per cent of these heat losses are due to infiltration, based on a nominal one air

Greenhouse Heat Infiltration

Insulation installation, by Manuel Fuentes.

Ecohouse Bariloche Sections

Site location and orientation.

Site location and orientation.

Insulation installation, by Manuel Fuentes.

change per hour. However, the quality of the windows will likely reduce this value to approximately 0.5 changes per hour and achieve a heat loss coefficient of less than 0.7 W m-3 K, half the recommended maximum value. A factor that increases heat loss is the north-facing glazed area. However, these losses are offset by useful heat gains on sunny days during colder periods of the year. The roof incorporates 150 mm of expanded polystyrene between the roof joists and a further 50 mm above the joists reaching 0.17Wm-3K. This method of incorporating a high standard of thermal insulation has the following advantages:

• no extra timber is needed to form the cavity where insulation is placed;

• the roof timbers are not exposed to indoor spaces, so rough sawn wood can be used, rather than more expensive sanded joists;

• continuous ceiling of tongue and grooved boarding, which is interrupted only by the principal roof trusses, provides an attractive and easy-to-maintain surface;

• two layers of insulation reduce the possible effect of thermal bridging.

The walls reach a value of 0.22 Wm-3 K. This value is achieved with a solid inner brick wall of 125 mm within an earthquake-resistant reinforced concrete structure, 150 mm of thermal insulation and an outer finish of timber boarding. This construction not only has an excellent level of thermal insulation, but also provides the following advantages:

• cold bridges are avoided, as there is negligible thermal connection between the inner brick and concrete structure and the outer finish;

• a thermal time lag of over 8 h is obtained, reducing possible overheating in summer and the cooling effect of sudden cold spells in winter;

• thermal admittance of the indoor side of the external wall is also high, 5.3 W m-3 K, allowing effective storage of daily solar heat gains;

• as the inner brick wall, with a dense render, is less permeable than the outer finish of timber boarding, there is no risk of internal condensation, even without a vapour barrier.

polythene vapoi

2 layers expi

fascia timber timbe polythene vapoi

2 layers expi gutter —

fascia timber timbe

Fascia Timber

polythene vapour barrier

Tyvek roofing membrane perlin

Section through wall.

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