To future proof your new home – Design for climate

by Nathalie Curtet, registered architect & GSAP Green Building Council of Australia www.compass.lndo.site

PASSIVE SOLAR DESIGN is to design a building/house that responds to the site, orientation, and climate to reduce the energy demand/load for heating and cooling the building, and to create a house that is comfortable to live in all year around.

The result is a house that regulates heating, cooling by natural means: use of the site orientation sun, wind and materials.

By reducing the need for energy (electricity from grid, gas, fuel): its carbon footprint, the passive solar house is both comfortable, economical, and sustainable. The remaining need for energy demand is balanced with solar power harvested from Photovoltaic Panels installed on the roof.

In Australia, Heating and Cooling energy demand accounts for 40% of energy use for a typical household. Energy efficiency should be one of the main considerations for building sustainable & affordable housing.

There are several tools to measure/predict the energy performance of a house with computer simulation programs and star rating.

Passive House is a design standard developed in Germany and suitable for Australian Climates. Passive House standards includes solar passive design principles with the addition of rigorous performance calculations and certification. The five principles for a certified “PASSIVE HOUSE” are: High Levels Thermal Insulation, High Performance windows and glazed Doors, Thermal Bridge free design of the building envelope, Airtightness, Heat Recovery Mechanical Ventilation to filter and regulate indoor & outdoor air quality/temperature.

PASSIVE SOLAR DESIGN is a key consideration for DESIGNING AN ENVIRONMENTALLY CONSCIOUS HOUSE. In addition, the following sustainability principles need to be implemented:

– water harvesting system and storage

– grey water collection and filtering system

–  hot water systems

– building footprint, rooms dimensioning

-indoor air quality for occupants health and wellbeing, zero VOC – Volatile Organic Compounds

–  construction type and selection of materials with extended life cycle, low maintenance requirements & reduced embodied energy considerations

– selections of insulations, type of glazing

– solar power /PV panels & batteries

–  A-rated fittings and appliances & type of light fittings for energy and water efficiency

The Passive Solar design techniques:

ORIENTATION

In the South Hemisphere, the main living spaces are designed to face the North orientation with larger openings to capture the sun heat during the cool/cold seasons and natural light.

The services areas are designed on the South side of the house with smaller openings, and larger area of walls to create a buffer from the cold/shaded side of a building.

The roof is designed with a North/South Orientation to maximise solar exposure for solar PV panels. The roof facing South will not capture heat. It is best to avoid   East and West facing roof orientation to prevent overheat/heat gain in the warmer/summer months.

GLAZING, SHADING & THERMAL MASS

North facing glazing: To harvest the sun energy in the cool/cold weather months when the sun is lower in the sky and store it for night-time by designing large windows/glazed doors oriented to the North (in the South Hemisphere) that will capture the sun heat in the living areas during winter & spring/autumn seasons.

Thermal mass like masonry walls, concrete floor will store the heat gained and radiate it later at night-time when the air temperature cools in the room.

In Summer months the sun is higher in the sky, Shading is required to protect the glazed openings from the sun heat during the summer months:  external operable louvres, pergola with deciduous climbers, large eaves and awnings.

Good quality smart glazing will improve and support solar passive design performance.

Double Glazing will prevent heat loss through windows and glazed doors.

INSULATION

Insulation prevents the flow of Energy through the building envelope. The R value represents the material resistance to heat flow. The higher the R Value, the greater insulation performance.

The building envelope construction materials and added insulation depends on the site climate. The building envelope is designed to suit the Climate and Site topography.

VENTILATION

Ventilation provides fresh air and removes stalled air (CO2) in the house. In a building envelope built with traditional methods, the infiltration of air occurs through materials and hairlines gaps in construction.

Natural ventilation is to promote the natural movement of air between the warm side and the cool side of a house: between the North side and the South side of a house in the south Hemisphere.

An elongated rectangular shape house facing North will allow to create natural cross ventilation in most living spaces.

To understand the house site climate and micro-climate, the ventilation design and glazed openings will allow to capture the cooling summer breezes as to prevent the cold winter winds to enter the living spaces.

At COMPASS ARCHITECTURE, the Passive Solar Design Principles were/are implemented in each project and result in creating some energy efficient, comfortable living, functional spaces in connection with their unique environments. The houses provide joy and wellbeing to the occupants.

FARMHOUSE, Brayton – The house design and forms respond to each passive solar design principle:

-northern orientation for living spaces and main bedroom,

-compact functional design,

-a thermal buffer to the south with service areas,

-natural cross-ventilation,

-thermal masses in floor and exposed brick wall (reversed brick veneer)

-double glazing to South facing windows

– high-level operable windows on North and South side for flushing hot air in summer months, -recycled face bricks,

-corrugated steel cladding for longevity and low maintenance.

The house is not connected to the grid and is entirely powered by the Solar PV systems with Batteries storage. The solar panels are installed on the 35-degree angle roof to maximise the solar harvesting during the winter months when the sun is at the lowest in the sky.

BEACH HOUSE, Coledale – The design incorporated most of the Passive Solar Design principles. However, because of the site complexity some principles had to be compromised like:

– the long western elevation with limited number of openings helped mitigate the solar gain in the summer months

-the glazing to the east in the living areas that was designed to encompass the views of the escarpment ridge and gully. The addition of operable external louvres in front of the double-glazing help mitigate the solar gain during summer months, but still allowed the views in cooler months.

–  a balance is achieved with smart design, good quality materials and good insulation in walls in roof and above ceilings and underfloor insulation.