Mystic Lotus

Self-Sustainable

Self-Sustainability is dedicated to the interests of Maximus & Florence.

How to design lighting for self-sustainable home?

Design for light

Thoughtful lighting design combines many daylighting and electric lighting strategies to optimise the distribution of light inside the building. It considers whole building energy impacts to minimise the building’s overall energy usage and integrates the design of daylight entry (through windows and skylights) with electric lighting, including controls. It takes advantage of shading strategies and glazing technologies to moderate the intensity and spectrum of the daylight admitted to the home, to minimise heat gain during the cooling season and heat loss during the heating season. It chooses the best window aperture sizes, glazing and shading design for each orientation to reflect the expected solar angles, heat gain and glare criteria.

Effective lighting design means putting light where it’s wanted and needed, and reducing or eliminating light elsewhere.

Daylighting design aspects

The science of ‘daylighting’ deliberately uses daylight to reduce or negate the need for electric light. Sources of daylight include sunlight, which is an intensely bright, directional beam, and skylight, a diffuse light of about one-tenth the illumination of sunlight. Daylight is dynamic, constantly changing its characteristics (intensity, colour, direction).

Design your new home to not require electric lighting during daylight hours.

A goal of all new homes should be to not require any electric lighting during daylight hours. Siting, orientation and size of the home come into play but every consideration should be given to minimising reliance on electric lighting during daylight hours.

Done correctly, daylighting design can deliver a net saving on energy consumed by the building. Done incorrectly, it most commonly increases the heat load on the home and its cooling energy consumption. If the daylight control system is poorly implemented, building occupants have to deal with glare and/or thermal discomfort using the most expedient means at hand (e.g. curtains drawn, operating air conditioner), which in turn negates any benefit that daylighting might have offered.

Some principles for daylighting in Australia

North facing windows introduce sunlight and daylight into the home, particularly in winter when the sun is lower in the sky and direct sunlight contributes to heating the house.

South facing windows (for latitudes below the tropic of Capricorn) predominantly introduce daylight without heat gains of direct sunlight — making them an ideal orientation for houses in warmer climates where home cooling is the main imperative.

Skylights and light tubes of appropriate sizing and design can let in light without adding heat in summer or losing warmth in winter.

Externally reflected daylight contains less heat than direct penetrating sunlight (i.e. the infrared heat is predominantly absorbed by natural and built environments).

Light coloured interior surfaces reflect more light and reduce the level of artificial lighting required.

Clerestories (with the associated eaves appropriately sized) are very effective at delivering daylight to the core areas of a home.

Sunny locations can exploit tubular daylighting devices — tubular skylights — which send direct-beam sunlight into the space below and are capable of delivering very high illumination levels when the sky is clear.

Direct sun should be excluded from task areas (particularly polished surfaces including kitchen benches and desktops) because of the high potential for glare and discomfort.

Internal sun penetration can be controlled with the least impact on an external view by vertical blinds on predominantly east and west oriented windows and horizontal blinds for predominantly northern (and southern, for north of the tropic of Capricorn) oriented windows.

Passive daylighting tips

To light task areas effectively, direct natural lighting from windows, skylights or light tubes (see Skylights) must be close to the task area. Windows should be part of the perimeter wall of the room being lit and skylights should be located in the roof directly above the task area to be lit.

Effective natural lighting is close to task areas.

Light tubes can be purchased for as little as $100 and installed easily by a tradesperson or capable DIY owner. They can replace a 60W light running for up to 8 hours a day in a poorly lit room, saving as much as $30 per year. They can thus pay for themselves in less than 5 years (varies according to length of use and combined wattage of lights on switch circuit).

Light tubes can replace a 60W light running for up to 8 hours a day in a poorly lit room.

Light shelves reflect daylight to penetrate deep into a building. They are suitable for north and south elevations but not the flat sun angles of east and west. A horizontal overhang with a high reflectance upper surface is placed above eye-level to reflect daylight onto a light coloured ceiling and deeper into a space.

By varying the height, angle and internal or external projection of a light shelf, you can control the pattern, intensity and depth of penetration of natural light (including sunlight) within a space. Light shelves should be light in colour and require frequent cleaning.

Not only do light shelves allow light to penetrate deeper into the room, they can shade near the windows to reduce window glare or create a sun patch. Exterior shelves generally provide more effective shade while interior shelves provide deeper reflected light. A combination of exterior and interior shelves works best to give an even illumination gradient.

Glass bricks are a useful source of daylight in walls that are close to boundaries or need privacy. Glass brick panels let in diffuse daylight while maintaining sound and visual privacy, and fire ratings.

Glass bricks let in diffuse daylight while maintaining sound and visual privacy in walls that are close to boundaries or face the street.

Light shelves reflect light deeper into rooms.

Electric lighting design aspects

Use of electric lighting in the home has two aspects: specific task lighting and creating a night-time ambience for a room or space.

Human vision has a very high dynamic range but perception of brightness shifts with the overall brightness of the entire space. The eyes adapt to low light levels at night and it is unnecessary to try to duplicate the high level of illumination available from daylight.

When considering lighting a space, work on points of interest within. The human eye is attracted to bright objects and accordingly should be rewarded with something of interest. By contrast, dark areas are of limited attraction but serve to accentuate (by contrast) the brighter objects of interest. Use highlights (about 10 times the ambient light level) to draw attention to key objects or spaces in a room, or for lighting specific tasks. Carefully select features to highlight (e.g. artwork, sculptures, and furniture items) and use the minimum effective highlight level so you don’t waste energy.

Reading lamps or table lamps are an effective, flexible and efficient means of giving higher task lighting rather than increasing general lighting of the entire space. They can also be part of the accent lighting for mood setting (e.g. table lamp on side table in lounge room).

Switches and controls

Time of use, hours of use, and occupancy of and traffic through spaces vary in the home. Switches and controls can be a very effective method of providing lighting only when and where it is required.

Some basic principles:

Provide multiple switches to control different lighting elements (ambient, accent or task) in a room where all may not be required all the time. One switch to turn on all lights in a large room is very inefficient. When choosing switching groups always begin with lighting that is needed most, such as that over the kitchen benches, then work backward. Place switches at exits from rooms and use two-way switching (for long hallways or stairwells) to encourage lights to be turned off when leaving the space.

‘Smart’ light switches and fittings use movement sensors to turn lights on and off automatically. These are useful in rooms used infrequently where lights may be left on (for very long times) by mistake, or for children, the elderly and people with disabilities. Built-in daylight sensors make sure the light doesn’t turn on unnecessarily during daylight hours.

Use timers, daylight controls and motion sensors to switch outdoor security lights on and off automatically. Similar controls are particularly useful for common areas, such as hallways, corridors and stairwells, in multi-unit housing. Some controls are not compatible with particular lamp types so seek advice.

Consider using solar powered lighting for garden and sensor security lights.

Modern dimmer controls save energy and also increase lamp life. However, reducing light output to 50% saves only about 25% of the energy (for a halogen lamp). If you dim some lights most of the time, consider replacing them with lower wattage lamps.

Most standard fluorescent and LED lamps cannot be dimmed (although this is improving), but special dimmers and lamps are available (check packaging or manufacturer’s website for information). When installing new light fittings and controls, check on compatibility.

Top 10 steps to lighting

Design a house to not need lights turned on during daylight hours.

Consider the orientation and layout of rooms to best use available daylight.

Use surface reflectance of light coloured surfaces, and well positioned pendant and wall lights, for good light distribution in a room.

Decide the type or types (e.g. general lighting, mood/background lighting, task lighting) of ambience you wish to create in each room during night-time use.

For more than one type of ambience, adjust light levels (dim lights) or turn different lights on or off through different switching circuits.

Create task or accent lighting with directional lighting.

Create general lighting with non-directional lighting.

Use warm coloured lamps for the home, except possibly for bathrooms and laundries where the cooler coloured lamps present an appearance of a clean, sterile space.

Before selecting a lamp, identify relevant attributes for illuminating each room (e.g. quick start-up, long life lamp, dimmable, multi-way switching).

For getting the ‘right amount of light’ to create the ambience you want, think about lumens, which measure of the total amount of visible light emitted by a source, not wattage (power).

Self-Sufficient:

Idea Material PV Lighting Solar Water Principles

Design:

Energy Lighting Food Water Location Budget Earthship Dome

Home:

Tiny Mobile Floating Passive Foundation