Self-Sustainability is dedicated to the interests of Maximus & Florence.How do I enable Passive Solar Design?There are two basic approaches to passive solar heating. One is the concept that where you expect a thermal mass material (like adobe or cob) to transfer the heat of the day into the house to warm it at night. This only works in certain fairly moderate climates, where nights tend to be cool and days are warm. In harsher climates that are hot or cold most of the time, or have seasonal extremes, then this strategy doesn't work very well, because unwanted heat or cold is transferred directly into the house, and there is no way to control this. The other approach to passive solar heating provides greater control and comfort in all climates. This is where the shell of the house is insulated and the heat of the sun is allowed to enter the building through glass. Ideally, the sun strikes thermal mass materials directly that are arranged in the floor, walls, or built-in features. In this scenario, the heat from the sun is collected in the thermal mass, which then releases this heat slowly over time...but this heat is not allowed to escape easily through the walls (or the glass, if it is insulated at night). This tends to provide greater comfort, because of the inherent stability of the temperature over time. Thermal mass materials will absorb the cold as well as heat, but with the sun, it is the radiant heat (infra-red) that is more readily absorbed by the mass material. This means that at zero degrees with the sun shining on thermal mass materials, they will warm up relative to the ambient air temperature...but when the sun goes down this heat gain will be dispersed in all direction. You need to insulate and place a moisture barrier on all of the walls and floors that are buried. You need to balance the amount of sunlight that is allowed to enter the house and be stored in the thermal mass with the particular climate where you are. A well-designed passive solar home generally also performs well in hot and humid locations because of the excellent insulation and the use of thermal mass materials on the inside. Often, the only part of the design that differs is perhaps less southern window exposure to reduce the solar gain somewhat. I especially like the idea of berming and earth-sheltering in these situations.Some designs that utilize uninsulated earthen walls (adobe, cob, rammed earth) would not be a good choice, but cordwood, strawbale, and some earthbag buildings would do just fine. Thermal mass is heavy, dense material that will hold its temperature for a long time and passes cold and heat through fairly easily. Insulation is light, airy material that tends to block the transfer of heat and cold, but does not retain a given temperature. What are the key principles informing Design For Place?Design For Place is informed by important design principles, helping you to take advantage of passive design for a more energy-efficient and comfortable home. Each of the universal principles aims to increase usability and livability for a range of people and circumstances. They influence the layout of the floor plans, the treatment of the elevations and cross-sections and the specifications of materials and construction type. Face north—use appropriate orientation In Australia, living areas should generally face north so that sunlight can come into the house during the day. This is essential in cold climates and it is a key way to reduce energy used for heating in winter. Allowing the sun to enter the house through glazed windows and doors heats the interior of the building during the day which reduces the need for mechanical heating during the colder hours overnight. The use of internal thermal mass to help store the heat generated during the day is a great way to further reduce mechanical heating needs. The exact orientation recommended for different climate zones is outlined under Star ratings and variations. Know where you live—respond to climate Where you live will have a major impact on how your house should be designed. Buildings will have different design requirements depending on their location across Australia. For example, design principles for a house in Canberra (cold climate) will differ to those needed for a house in Darwin (tropical climate). Ensuring that designs pay attention to the relevant design principles for the climate zone is important for avoiding issues such as inappropriate heat loss or heat gain, insufficient cross-ventilation, or too much stored heat. Appropriate specifications for your climate zone are detailed under Star ratings and variations with case studies and further background in Design for climate. Let the light in—provide appropriate levels of natural light When a house has its living spaces facing north, windows and doors can let in appropriate levels of natural light. Effective ‘daylighting’ can reduce or even eliminate the need for electric lights during daylight hours. Careful placement and sizing of windows, the use of skylights and light tubes, as well as light-coloured interior surfaces can maximize benefits, while avoiding additional loads on heating and cooling. It is good practice to have the majority of glazing facing north, with smaller amounts facing east and west because they receive the strongest sun and are the most difficult to shade. For tropical climates, southerly windows can allow light but not heat into your house. Put on layers—provide appropriate levels of insulation Building insulation stops the unwanted transfer of hot or cold air from inside to outside and vice versa. In winter, it ensures that heat from mechanical heating or the sun is kept inside the house, and in summer it prevents the cooling effect from air conditioning or thermal mass inside the house from escaping. Insulation is generally placed in ceiling spaces, under roofs, in walls, under suspended floors and sometimes underneath and around concrete slabs. Insulation is important in all climate zones, but is particularly relevant in colder climates where insufficient insulation allows heat to filter out through ceilings, roofs, walls and floors. Pull the shades down—provide appropriate levels of external sun-shading Windows and doors should be shaded from the summer sun by eaves, pergolas, sun-hoods or external blinds. Effective shading can block up to 90% of the heat from direct sunlight, reducing heat from north-facing glazing in summer. Shading devices may be fixed or operable and should be correctly placed and sized to respond to the sun’s height at different times of the year. As a basic rule, north-facing eaves should be narrow enough to allow the low-angle winter sun to enter the house, but wide enough to block the high-angle summer sun. The type and size of these devices will vary depending on your climate zone, location and budget. Get some fresh air—provide appropriate levels of natural ventilation Allowing ventilation through a house is important in all climate zones. Design should maximise benefits from cooling breezes in summertime, particularly in warmer climates. Cool evening breezes can flush out the warm air that has accumulated in the building during the hot daytime hours. For natural cross-ventilation to occur, it is best to have openable windows on opposite sides of a room to allow breezes to pass through. High openable windows can also be useful to allow hot air to be flushed out at night while doors underneath are locked. Good ventilation is also important for healthy indoor air quality. In colder climates where the building is sealed up with the heating on for long periods during winter, selecting and positioning windows so the building can be ‘flushed out’ when weather conditions allow and breezes are at a comfortable temperature is important.
 
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