D
aylighting is the art and science of
managing natural light to minimise
the use of artificial lighting, reduce
carbon emissions, and positively affect the
performance, mood and well-being of
people occupying a particular space.
Designing, predicting and planning for the
impact of daylighting in a space is often
misunderstood however. Daylight modelling
removes the design mystery and determines
the daylight requirements for any building.
It is not a new science, but one which is
increasingly important as reduced energy
consumption is a continuing major
consideration – as well as statutory
requirements (such as European workplace
directives) and personal wellbeing.Part of the design
It’s often a mistake not to use daylight
modelling as part of the original concept or
design. Consequently, it is beneficial that
this service is used early to help achieve the
best possible results for the client and to
form part of the overall building strategy
and goals.
For example, the service can help with the
documentation required to achieve
BREEAM’s health and well-being credit
for visual comfort (HEA01) which requires
that 80 per cent of the occupied space meets
a minimum daylight factor of 2 per cent
(3 per cent for ‘exemplary’ level).
It can help architects and specifiers with the
following calculations:- Quantity of light transmitting materials
- Location of light transmitting materials
- Required transmission level of the light
transmitting materials - Glare analysis.
Daylight modelling can help achieve an
exact brief from the client – for example the
lux level requirement or to address concerns
about solar heat gain. It can help quantifydaylight transmitting products, determine
optimal light transmission and help with
positioning on a building to prevent glare
issues and provide interior lux levels.
Reports can be looked at from a cost
point of view, and recommendations can be
made depending on the results. A good
example of this is for ‘value engineering’,
where daylight modelling examples may
show that windows can be reduced in size
to save money yet still achieve the desired
lux levels. The report could include any or
all of the following calculations:Lux level
Lux is equal to one lumen per square metre.
In photometry, this is used as a measure of
the intensity, as perceived by the human eye,
of light that hits or passes through a surface.
For example, sports halls and classrooms
would be expected to have lux levels of
between 300-400.Architectural journalist Gideon Sykes looks at the latest advances in
daylight modelling and how it can help architects and specifiers determine
the right light levels for their projectsShedding light on
daylight modelling
Daylight modelling may
show that windows can be
reduced in size to save
money yet still achieve the
desired lux levelsEXTERNAL ENVELOPE 65ADF NOVEMBER 2019 WWW.ARCHITECTSDATAFILE.CO.UK
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