Using what is natural, healthy and for free should be our first aim when we intend to green our lifestyles. Wind, sun and rainwater are such resources. These three sustainable assets can be harvested with sometimes small yet clever tricks, at other times with more elaborate and costly measures. 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 largely achieved through incandescent and halogen light bulbs, which convert more than 80% of the energy used into heat rather than light! More conscious households have now introduced and installed CFLs (compact fluorescent lights) or the newer and 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 occur during the day. How many of us have rooms that never have enough 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. Doing so can generate real savings that often last forever with practically 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. Here are the most common options:
You remember in my previous article ‘Keeping warm in Winter’ we talked about to the relationship between heating a home and sun radiation coming through windows. 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.
Daytime lighting solutions
1. More windows
Adding windows is probably the step that comes to mind first. It sounds really simple and often is, yet might induce considerable costs. Larger or just more windows have a great effect. Its is best if the new window only allows daylight, rather than direct sunshine to penetrate the room. Heat build up during the summer months is thus avoided.
2. 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 considerably decrease the demand for artificial lighting. For privacy reasons these windows can either be frosted or situated above eye level, and double glazed for sound protection.
3. Glass doors
The same principle as for indoor windows applies here. Why not change an existing door to a glass door creating about 1m2 of natural daylight penetration? Even glass entrance doors leading to otherwise often dim entrance 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.
Bathrooms, pantries and passages sometimes have no or only insufficient windows. South facing rooms often have windows but seldom receive enough light through them to suit work requirements. These rooms tend to be dark and dim. Installing an extra window might not be an option. If these rooms are nestled 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 aluminium tubing system to a diffuser in the ceiling flooding this part of a home with an even spread of energy saving natural light.
6. Frosted glass
Residential areas are habitually densely populated. For privacy reasons many a window has a permanent curtain drawn to ensure privacy from neighbours. Sometimes this ‘curtain’ is opaque or just a cloth or a kikoi which cannot 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, glass specialists will sand-blast existing window panes.
7. Flexible curtains
Installing a curtain rail with twin curtains, one with translucent material and the other one with opaque, allows not only for flexibility and ease of operation, but offers the added advantage of insulation during the winter.
Very similar to the curtain issue, windows overgrown with bushes and trees, ivy or a creeper obstruct 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 enables you to easily adapt to the seasons: Less light and cool air in summer, more light and warmth in winter.
9. Layout of furniture
How you place your furniture in a room can also contribute to the illumination of your work areas during daylight hours. If a desk or workbench was situated in front of or close to the window, the need to switch on energy hungry light bulbs can be minimized if not eliminated.
Colour is known to either reflect light or swallow light, i.e. light colours as the name suggest reflect more light than dark colours. This means that both natural and artificial light sources are either supported or hindered by the colour of the floor, walls or even furniture. For instance, changing the wall colour from a darker to a very light colour such as beige or white has a significant effect. Now the usual daylight has a chance to generate a good and workable illumination level.
In a similar way mirrors don’t only reflect light, but even redirect a substantial amount of light. A strategically placed mirror can reflect daylight into a darker corner of a room or passage.
The only issue that now remains is that daylight is only available during daytime. At night different measures apply. Those we will discuss in a future story.
By Martina Gluckman
Martina is a residential eco auditor and an expert in turning existing homes into energy and water efficient households, whereby substantial savings on utility bills and carbon emissions can be achieved. She teaches residential eco-auditing through environmental education leader Global Carbon Exchange.
Her company Tiptoe – Leave No Footprint is an eco consultancy which specialises in the residential sector offering energy, water and eco audits. The service is designed to help identify and eliminate inefficiencies in a home, and promote change to a greener more sustainable lifestyle for the owner.