PASSIVE DESIGN · nZEB- nearly zero energy buildings

Passive design has been used as a strategy since the earliest human structures. There is no valid universal solution for a passive building: every case will be specific for climate, microclimate, geographic context and culture.

Yet, the approach to be followed, holistic and innovative is universal. Passive design techniques can be applied most easily to new buildings, but existing buildings can be adapted.

The aim is to use design strategies which optimise comfort levels while reducing to a minimum heating/cooling costs and carbon emissions.

In passive building design, building elements such as windows, walls, roofs and floors are made to collect, store, reflect, and distribute solar energy in the form of heat in the winter and shade in the summer. This is called passive design because, unlike active heating systems, it does not involve the use of mechanical and electrical devices.

The key to designing a passive building is to understand the local climate and perform an accurate site analysis. Aspects to be considered include orientation, building form, window placement, size and glazing type, thermal insulation, thermal mass, natural ventilation and shading. Active renewable sources are the perfect complement where energy, heat and/or cooling generation is required.

Some passive design strategies used are:

Direct and indirect solar gain through glazing for space heating.

Strategic window design, conservatories, trombe wall.

Shading systems; verandahs, canopies, pergolas, screens, blinds, shutters.

Solar water heating systems using a thermo siphon.

Use of thermal mass to reduce temperature swings.

Extensive insulation of walls, ground floor and roof.

Elimination of cold bridges through careful detailing.

Enhanced natural ventilation; cross ventilation, solar chimney.

Earth sheltering and use of vegetation on building facades and roofs.