all the elements required for plants to survive, light
is perhaps the most important. Without light,
plants die very quickly. But how do you know which
plants will survive in the different light levels that
are found in a building? Will the same species
thrive as well in a well-lit atrium as in a seldom-used
conference room? Can you get the 'look' you are
after if the light isn't right?
section of module 3 will help you find out how plants
use light and how you can select plants that will survive
under different light levels.
do you know how much light you have?
only way to be sure about the amount of light that is
available is to measure it.
Different types of measurement
Light can be measured in several different ways, including
the energy of the light, the quantity of light or the
brightness of the light. Light meters are available
that measure light in all these forms, but for our purposes,
you only need to consider brightness (illumination).
to find out about other types of light measurement.
The brightness of light as experienced by the eye (illumination)
is measured in lux (foot candles in the USA. 1
lux = 0.093 foot candles, which means that there are
approximately 10 lux to 1 foot candle). This is the
form of light measurement that most interior landscapers
and architects use.
What do we use to measure light?
The only way to accurately measure light is to use a
light meter. NEVER rely on your eyes and your judgement
about the light levels in a room, because your eyes
adapt very quickly. No matter how much experience you
have in specifying plants, you can never trust your
eyes alone when making a decision about light levels.
Light meters, like
any other scientific instrument are totally objective.
They can only tell you how much light there is at the
centre of the sensor at the time of the measurement.
They cannot make allowances for the time of day, the
direction of the sun or the type of window blinds that
might be in place. However, they are fairly simple to
use, just as long as you follow some straightforward
rules. Click here
to download information on measuring light.