Sunlight: Green, Free and Sustainable!

Using what is natural, healthy and for free should be first aim when we intend to green our life styles. Wind sun and rain water are such resources. These three sustainable assets can be harvested with sometimes small yet clever tricks, at other times with more elaborate and cost measurements. But once implemented they all…

Using what is natural, healthy and for free should be first aim when we intend to green our life styles. Wind sun and rain water are such resources. These three sustainable assets can be harvested with sometimes small yet clever tricks, at other times with more elaborate and cost measurements. But once implemented they all have one thing in common: zero pollution and of course long lasting savings.

Residential lighting is considered an energy hungry area: 6% of world-wide energy consumption is allocated to light private homes. Currently lighting is widely achieved through incandescent and halogen light bulbs which unfortunately convert more than 80% of the energy used into heat rather than light. More stylish households have now introduced and installed CFLs (compact fluorescent light) or newer even more efficient LEDs (light emitting diodes).

For many of us changing light bulbs is the most obvious option to reduce energy demand in terms of lighting, but it is not the only one. Another is to reduce the need for artificial light in the first place, particularly those needs that occurs during the day. How many of us have rooms that never have sufficient daylight and need artificial lighting throughout the day? How often do we switch on an extra light source above our working area even at midday? In my experience there is always a way to reduce or even eliminate this energy demand during daytime hours before all else. Doing so can generate real savings that often last forever with practice zero pollution to our environment. When we begin to green our lighting needs during the day, we have to work with the most powerful source of light we know: our sun. In this article I would like to elaborate on different ways to eliminate daytime use of man-made luminaries by letting in the sunshine.

In my work as an eco auditor I look at the lighting performance of every room. I examine the needs of the home owner in this particular room and establish how natural daylight can be harvested to suit these needs. In this article I would like to share the most common options with you:

Before I go on, I would like to remind you about my previous article “Keeping warm in Winter”. In this article I have talked about about the relationship between heating a home and sun radiation coming through windows. I would like to repeat that whenever we think of sunlight entering rooms, we also have to consider heat gain or heat loss through the very same window. Balancing warmth and insulation with daylight harvesting is important. All in all flexibility is the key and applies to most options below.

More windows
Adding windows is probably the step that comes to mind first. It sounds really simple and often is, yet may have reasonable costs. Larger or just more windows have a great effect. This is best done in a way that the new window only allows daylight rather than direct sunshine to penetrate the room. Heat build up in summer is so avoided.

Indoor Windows
Letting daylight in is not limited to windows through outside walls. Even inside windows leading from a lighter to a darker room can consider decrease the demand for artificial lighting. For privacy reasons these windows can either be frosted or positioned above eye height, and double glazed for sound protection.

Windowed doors
The same principle as for indoor windows applications here. Why not change an existing door to a windowed door creating about 1m2 of natural daylight penetration? Even windowed entrance doors leading to otherwise dimen entry areas, yield a great deal of daylight and are often quite economic to convert.

Skylights come in many forms suiting many different requirements and budgets. The best of course would be a skylight that can be opened easily to release any heat build up through increased radiation.

Solar tubes
Bathrooms, pantries and passes sometimes have no or only insufficient windows. South facing rooms often have windows but seldom receive light light through them to suit work requirements. These rooms tend to be dark and dim. Installing an extra window may not be an option. If these rooms are nested under attics, skylights are no option either, but solar tubes are. A solar tube's natural lighting system captures the sun's light with a solar reflector inside an acrylic dome. The light is directed down a highly mirrored aluminum tubing system to a diffuser in the ceiling flooding this part of a home with an even spread of energy saving natural light.

Flexible curtains or frosted glass
Residential areas are habitually densely populated. For privacy reasons many a window has a permanent curtain drawn to ensure privacy from neighbors. Sometimes this “curtain” is opaque or just a cloth or a kikoi which can not easily be opened and closed. This means it is closed most of the time and occupants tend to supplement the room with artificial light measures during the day. Frosting these windows makes a lot of sense as no matter what the situation is, the window will never be transparent. Frosted foils and frosting sprays can be bought at any hardware store. Alternatively, a glass specialist will sand-blast existing window panes.

Installing a curtain rail with twin curtains, one with translucent material and the other one with opaque, allows only for flexibility and ease of operation, but offers the added advantage of insulation in winter.

Very similar to the curtain issue, overgrown windows through buses and trees obstruction daylight from entering rooms. Cutting back overgrowth as much as possible or even removing it entirely, is a great solution for daylight harvesting. Replacing this overgrowth with a deciduous plant is another option and adds the possibility to adapt to seasons: Less light and cool air in summer, more light and warmth in winter.

Layout of furniture
The position of furniture in a room can also play a part in the need for man-made illumination in work areas during daylight hours. If a desk or workbench was located in front or close to the window, the need to switch on energy hungry light bulbs can be minimized if not eliminated.

Color is known to either reflect light or swallow light, ie light colors as the name suggest more light than dark colors. This means that both natural and artificial light sources are either supported or hindered by the color of the floor, walls or even furniture. For instance, changing the wall color from a darker to a very light color such as beige or white has a significant effect. Now the usual daylight has a chance to generate a good and workable lighting level.

In the same line as the color on our walls a mirror not only reflects light, but even redirects a substantial amount of light. A strategically placed mirror can reflect daylight into a darker corner of a room or passage.

So, from now on your home should be able to let the sunshine in! After that the lone issue is that daylight – as the name suggests – is available during daytime only. When there is no more daylight, different measures will apply. Hopefully we'll have another chance to talk about those energy saving methods sometime in the future.