Control for Conservatories - ‘Controlling the
** An article all about making
your conservatory more comfortable and useable all
year round – sponsored
by: Insupolycarbonate™ Roofing **
When it comes to Climate
Control in a conservatory or sunroom there are usually
four distinct markets:
purchasers of new conservatories: People looking for information
on products that can
be incorporated into their conservatories from new
which will ensure that they can use their conservatory
in comfort all year round.
Conservatory Owners: People looking to upgrade, refurbish, update
or maintain their existing
conservatories so that they are use-able in comfort
all year round.
Companies: Business people looking for products that can be
added to their range for competitive
advantage, or to meet the competition. Or for information
on how to solve customers problems by improving the
environmental design of their conservatories.
and Designers of Conservatories, Atria or Roof
Glazing Systems: Individuals looking
for information on products that can improve the environment
and make the areas below the glazing usable in comfort
all year round.
To simplify the information gathering
process we have divided the information in to four
separate pages – each
answering some of the most common questions asked by
conservatory buyers and owners.
In addition everyone (trade and
general public) are welcome to request the very informative “Guide
to Controlling the Conservatory Environment”
Prospective purchasers of new conservatories:
Question One: I have heard that my new conservatory
will be unusable on sunny days in summer because of
high temperatures caused by the sun shining through
The power of the sun is generally underestimated.
A typical conservatory receives a peak of 8 kW of solar
energy per hour on a clear sunny day in June, which
is the equivalent of 8 single bar electric files stacked
in the centre of the conservatory. It is not unusual
for temperatures to reach 40 to 50C, (100 to 120 F).
This large amount of energy can be excluded to reduce
temperatures to comfortable levels with the correct
selection of shading systems in the original design
of the conservatory.
All conservatories facing east, south and west suffer
from problems of high temperatures due to the sun shining
through the roof glazing, in summer up to 80% of the
solar heat enters through the roof glazing as the sun
is high in the sky.
North facing conservatories are not entirely problem
free unless they are on a high gable end, or three
storey height properties. When fitted to bungalows
conservatories suffer from April onwards as the sun
is above the roof pitch on cloudless days. Many conservatories
fitted to traditional two storey properties experience
overheating problems as the shadow cast by the house,
which provides protection, only extends to: 4 metres
(14 feet) in April and August, 3 metres (10 feet) in
May and July, and only 2.8 metres (9 feet) in June.
If the projection of your conservatory into the garden
exceeds 3 Metres (10 feet) you will experience overheating
Side glazing, unless it extends from floor to roof
height, is not a major cause of overheating because
when the problem exists, May, June, July and August
the sun is high in the sky and predominantly shines
through the roof.
Two: How important is ventilation in controlling
high summer temperatures?
Ventilation is an important consideration but only
after the excessive solar heat has been reduced to
manageable levels by correct selection of the shading
system. Otherwise the available ventilation is rendered
ineffective because it is completely overwhelmed with
The most important considerations
are that the air inlet and outlets are of equal dimensions,
as the ventilation
rate is governed by the smallest opening, and they
must be positioned to allow ‘cross flow’ of
air across conservatory. The design of the windows
is important, conventional side hung openers are the
most effective, top hung and inward opening tilt and
turn types are far less effective. When the conservatory
is closed it is important to have trickle flow ventilation
with the security catches providing at least 25mm,
or 1-inch gap. Roof lights are a very effective method
of ventilation, as they provide a much higher level
of ventilation due to the chimneystack effect resulting
from their height.
Three: Will my conservatory be cold in winter
and uneconomic to heat. I understand that new Building
regulations will shortly be introduced concerned
with insulation, what are these regulations and how
will they effect comfort in my conservatory?
It is anticipated that in the
near future conservatories will be subject to Document ‘L’.
This is a insulation standard that will form a part
building regulations for all new conservatories. This
has been introduced for a number of reasons the principal
one being that there is now more glazing sold for use
in conservatories than all other applications put together.
Also conservatories are being incorporated into houses
by the removal of patio doors, and integrated into
family rooms and kitchen areas in new homes. Consequently
the government has identified the conservatory as a
significant cause of the Carbon Dioxide emissions that
it wished to control to meet its climate change targets.
Document ‘L’, amongst
other things, is concerned with both side and roof
glazing and specifies
a minimum heat loss factor of 2.0 units of energy escaping
per M2 of glazing, which will shortly be reduced to
1.8. The previous norm for double-glazing was 2.8 units.
This improvement in performance
has been brought about by the incorporation of low
E glass into double glazed
units, Pilkington’s ‘K’ glass is
probably the best known of these but all glazing companies
offer a similar product.
The advent of these regulations has focused attention
on providing comfortable winter temperatures and most
glazing companies now offer glazing of significantly
higher specification than those demanded by the new
regulations. Typical values for Glass and Polycarbonate
roof glazing range from 1.2 to 1.5 units of heat loss
based on the incorporation of argon gas in glazed units,
and transparent heat reflectors in Polycarbonate roofing.
The use of these products, with adequate heating systems,
enables conservatories to be used economically in comfort
throughout the winter.
A drawback of the improvement
in winter insulation is that in summer it is more
difficult for the sun’s
heat to escape out from the conservatory. As a consequence
there is now a greater need for summer solar protection
in conservatories that conform to the new Building
It is important to understand
that ‘K’ glass,
and similar glasses, provide no protection in summer
from solar heat, special types of glass with solar
reflecting properties fulfil this purpose.
Question Four: I have sensitive eyes and suffer from
glare; will this be a problem in my new conservatory
because of the large area of glazing?
Glare can be a problem and cause discomfort. It depending
on the sensitivity of ones eyes, and as we grow older
the problem increases because the pupil in the eye
becomes slightly hazy, as a result scattered light
causes glare. The selection of good conservatory glazing
and appropriate wall and floor finishes can solve the
problem of glare caused by scattered light.
The correct selection of roof glazing in the original
design of the conservatory goes a long way to overcoming
the problem since it is greatest in the late Spring/summer/early
Autumn when the sun is overhead. Low-level glare can
be a problem at other times of the year through the
side glazing and this is best dealt with by blinds.
It is important to avoid lightly coloured reflective
surfaces on the walls of the conservatory, and most
important to select floor finishes which are non-reflective.
The best colours for these surfaces are pastel shades;
white floor tiles should be avoided as they reflect
bright light directly upward into the eye below the
eyes natural shading devices, the eyebrows and eyelashes.
Five: I am worried about fading of my furnishings.
Have you any advice on what I need to do to combat
fading and the types of furniture most suitable for
Because the conservatory is fully glazed furnishings
are much more susceptible to fading than when in the
house. However there are certain precautions you can
Ultra-violet filters can be incorporated into the
glazing, which filter out 99% of the ultra-violet rays,
the main cause of fading. The main problem is the roof
glazing in summer. This is when the sun is at its brightest
and highest in the sky.
Solar heat also plays a part, and a reduction in summer
temperatures can be extremely beneficial in reducing
fading. The fading process is a chemical reaction and
accelerates with increased temperature.
Integrated shading systems incorporate ultra-violet
filters can be fitted to help combat both fading and
high summer temperatures.
Correct selection of fabrics is important. It is not
commonly known but there is a grading system for the
stability of dyes, the British Colourfastness scale.
This grades dyes from one to five in order of stability.
Most European manufactured fabrics are graded at 2
to 4. The highest grade is suitable for conservatory
Antique furnishings and fabrics, musical instruments,
and wooded furniture susceptible to cracking due to
heat are nor recommended for use in conservatories.
Question Six: Would it be wise to install air-conditioning
and how effective is it at controlling high summer
The direct sun temperature, and
the shade, or air temperature determines our thermal
comfort. These temperatures
are directly analogous to the sun and the shade temperatures
quoted in the tropics. The sun temperature is the main
cause of discomfort in conservatories it is very personal
as it results from the sun shining directly on our
body and clothing. It is often up to 15 °C (27 °F)
higher than the shade or air temperature and is the
principal cause of discomfort.
Air-conditioning does little to reduce the sun temperature
as it only effective at reducing air or shade temperatures,
and in any event the capacity of the units available,
around 1.5Kw cooling, is overwhelmed by the magnitude
of the solar heat entering the conservatory 8Kw. Apart
from the running costs air-conditioning units are also
noisy. This is why some people have found air-conditioning
in conservatories generally to be ineffective and expensive.
Everyone (trade and
general public) is welcome to request the very informative “Guide
to Controlling the Conservatory Environment”
Editorial provided by and sponsored by: Insupolycarbonate™ Roofing
the INSU websites at: http://www.insu.co.uk and