Conservatory Too Hot? - Get the "Guide to Controlling the Conservatory Environment’
** An article all about making
your conservatory more comfortable and useable all
year round – sponsored
by: Insupolycarbonate™ Roofing **
Question One: In summer my conservatory is unbearably
hot and glares, and I am worried about fading of my
furniture and furnishings. What can I do to overcome
There are two principal causes of summer discomfort
in conservatories: high temperatures due to sun shining
through the roof, and glare from bright sunlight directly
entering the eye, or reflected from light coloured
Two factors affect thermal comfort:
The unshaded, direct sun temperature, and the air
temperatures are analogous to the temperatures in the
sun and shade quoted in the tropics. The direct sun
temperature is very personal; it is the temperature
we feel personally on our skin 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.
It is essential, for comfortable
use of the conservatory to reduce temperatures to
27°C (82°F) or below
but unfortunately temperatures often reach 40 to 50°C
(100 to 120°F) or more.
Comfortable temperatures can
only be achieved by installing solar protection in
the roof glazing since up to 80%
of the sun’s in summer enters through this. The
most effective way to do this is to reflect the sun’s
heat out before it enters the conservatory. A variety
of methods can be employed depending on the circumstances
and magnitude of the problem from transparent heat
reflective shading incorporated within the glazing,
to external and internal shading systems.
Because the sun temperature is caused by the sun direct
shining on our body it is not reduced significantly
by air conditioning, this is why air-conditioning in
conservatories is generally found to be ineffective.
Air-conditioning is it only effective at reducing shade
or air temperatures, and the cooling capacity of the
units available, around 1.5Kw, is overwhelmed by the
magnitude of the solar heat entering the conservatory
8Kw. In addition they are noisy and expensive to run.
by bright glare: This is generally
a part of the summer problem but its effect is often
not fully recognised until a solution is demonstrated
which provides relief. Shading solutions that protect
against high temperatures generally also protect against
direct glare through the roof glazing. Reflected glare
from lightly coloured surfaces also causes problems.
It is important to avoid the use of light coloured/reflective
coloured surfaces on walls and especially the floor.
The importance of the floor cannot be underestimated
as bright reflected glare from this can enter the eye
directly below the eyes natural shading devices, the
brow, eyelids and lashes.
The main causes of fading and deterioration of furniture
and furnishings are Ultra-violet rays and heat.
Ultra-violet rays can be reduced by up to 99% by treatment
of the glazing with transparent Ultra-violet filters.
These are incorporated as standard protection into
the transparent heat reflectors which are available
for installation to glass or polycarbonate roofs, or
side glazing, for controlling high summer temperatures,
and reducing winter heat loss.
The use of these transparent products provides all
day protection and overcomes the inconvenience of using
throws to protect furniture.
Question Two: I would like to use my conservatory
throughout the year as part of the house but it is
unbearably hot in summer and cold in winter. How can
I upgrade it for year round use?
The lower and upper limits of
the range of comfortable temperatures for must residents
in the UK is between
20°C( 68°F) to 27°C( 82°F). If a conservatory
is to be integrated into the home it must be maintained
between these temperatures. As these temperatures mark
the lower and upper limits of comfortable use of the
conservatory, any temperature outside of the range
renders the conservatory totally unusable.
In summer up to 80% of the sun’s
heat enters through the roof glazing, and in winter
up to 65% of
space heating escapes through the roof glazing. The
key therefore to controlling temperatures is upgrading
the insulation standards of the roof. This can be done
in several ways.
Existing glazing can be upgraded by incorporating
heat reflectors in-situ to deal with the summer problems
of heat and glare. The extent of winter insulation
improvements will depend on the way the conservatory
faces, and the current quality of the glazing.
Another factor which will have
an important bearing on the choice of solution will
be the age and type
of glazing. For example early forms of polycarbonate
roofing have a limited life expectancy, as low as twelve
to fifteen years in some cases, and single glazed roofs
can be of variable quality. In such cases it may be
more economical to simply replace the roof glazing
panels with new panels conforming to the forthcoming
Building Regulation standard Document ‘L’,
which incorporate solar heat reflectors for summer
comfort. An additional economic attraction, if the
roof needs to be replaced soon, is the complete works
of upgrading and replacement can be undertaken at the
In cases where the roof glazing has a reasonable life
expectancy summer heat reflectors, and upgrading of
the winter insulation value of the roof glazing can
be simply done in-situ.
Upgrading of side window glazing is relatively simple
but in practise unless sealed units are misted and
replacement is for cosmetic reasons this work is very
much a second priority.
Question Three: My conservatory is unbearable cold
in winter and impossible to satisfactorily heat, and
sometimes condensation forms on the inside of the glazing,
which drips onto my furnishings. Can I upgrade the
glazing to eliminate this problem so it can be used
it comfort during winter, and what type of heating
should I install?
Conservatories that face north
or which are shaded by neighbours homes receive no
benefit from the sun
in winter since at this time of year the sun is low
in the sky, they therefore require a much higher standard
of insulation than those facing south. Most conservatories
constructed prior to 2003 have roof and side glazing
of a relatively low insulation standard of ‘U’ value,
or heat loss factor, of between 2.8 and 6. The insulation
standards in these conservatories is well below the
forthcoming Building regulations standard Document ‘L’ which
requires a ‘U’ value or heat loss factor
of 1.8 or less. In the case of north facing, or shaded
glazing, which receives no winter benefit from the
sun, a value of 1.4 or less is advisable.
The consequences of poor standards of insulation can
be far reaching. In the case of single plain or wired
glass, or twin wall polycarbonate glazing typical of
conservatories built before 1990 condensation drips
can be a major source of annoyance, and the very low
temperature of the glazing can cause discomfort due
to down draughts.
These problems and those of winter
discomfort can be simply resolved by either replacing
with modern standards or insulation which have ‘U’ values,
or heat loss factors, of down to 1.2, or the fitting
of lightweight transparent insulators below, or above
the existing glazing. In the latter case the high cost
and inconvenience of replacing the roof glazing is
avoided and ‘U’, or heat loss factors,
of below 1 and approaching those of a single brick
wall can be achieved.
The type and capacity of heating system used in the
conservatory can have a profound influence on comfort.
Radiators are often installed with scant disregard
to their correct size or indeed if the boiler has adequate
capacity to supply the additional heating needs of
the conservatory. In the latter case the result is
inadequate heating in both the conservatory, and the
It is important once the insulation
standard are satisfactory to have the adequate levels
of heating. These are difficult
for plumbers to determine, as calculation tables for
the heating needs in conservatories are not available.
Plumbers tend to work off the information they have
for the house, which can be very hit or miss. Provision
should be made for a heating capacity of around 0.3
Kw per sq metre of floor area to cope with temperatures
down to -4° C (25 °F) in conservatories with,
or upgraded to, modern standards of insulation.
Several types of heating can
be used in conservatories; each has its advantages
and disadvantages. Document ‘L’ frowns
on systems, which are tied into the central heating
system for the home. Many homeowners disregard this
advice for economic reasons, which are not, necessarily,
justified in practise.
Question Four: My conservatory was one of the main
reasons I bought my house. After recent rain it is
leaking. I have also noticed that some of the roof
panels are discoloured, and side window panes misted.
I have contacted several conservatory and glazing companies
to arrange refurbishment of the conservatory and repairs
but no one seems interested?
Most conservatories carry a ten year guarantee but
unfortunately the identity of the builder of the conservatory
is the last thing on the mind of buyers and sellers
of homes, and this important information is not passed
on when the house if sold. Even when this information
is available the new homeowner may find that the conservatory
company has gone out of business, or the conservatory
company is reluctant to transfer the guarantee.
do not wish to become involved with maintenance,
refurbishment and repair work because
it is not always easy to identify the source of leaks
and affect their repair, as this is specialist work. Also companies know that by undertaking the work the
homeowner will expect follow-up service if the problem
is not resolved which can be expensive and time consuming
on what was in the first place a small/ low value job.
This is why it may be difficult to find anyone prepared
to undertake this work and the after sales commitment.
Fortunately there are companies with the specialist
knowledge required and the work can be relatively straightforward.
For example: leak problems in polycarbonate roof conservatories
are often due to slippage of roof panels due to the
prodigious expansion co-efficient of this material
and the fact that they have not been satisfactorily
secured from the outset. Deterioration of flash-band
flashing, a low cost alternative to leading which can
be installed without chasing out the brickwork is also
a common problem. As are leaks due to movement of the
Finial, the embellishment on the pitch of the conservatory
roof, and the cladding at the top of the windows adjacent
to the gutter. Re-aligning and sealing of these elements
normally solves these problems.
In more serious
cases there may be movement, or ‘spreading’,
of the conservatory roof structure that pushes out
the side windows. This can occur if there is inadequate
bracing of the roof structure with tie bars or a ring
beam. The consequence is that the side windows are
forced outward, and may bow leading to gaps in the
structure, movement of roof panels, leaks and wind
Depending on the type of conservatory, and magnitude
of the problem, it is possible to retrofit tie bars
and jack in the out of alignment so that the roof panels
and other elements can be repositioned and refitted.
In more serious cases the conservatory may have to
be condemned as an unsafe structure.
Discoloured roof panels in polycarbonate-roofed conservatories
occur because: the original roof panels have being
fitted upside down, or the panels need to be replaced
as they have reached the end of their life. Polycarbonate
roof panels incorporate an external ultra-violet filtering
layer, which protects the material against deterioration
due to the sun and gives the panels their longevity.
If the panels are fitted the wrong way up there is
no sun protection and the panels degrade. The ultra-violet
protecting layer has a limited life that determines
the life of the panels, when this is reached the panels
degrade and must be replaced. In conservatories built
before 1995, especially those fitted with twin wall
polycarbonate, the life expectancy of the panels is
as low as 12 to 15 years, and many roofs from this
time are coming up for replacement.
Failure of the panels goes through two stages. First
discolouration, crazing and embrittlement, failure
at this stage can occur due to hailstone damage. The
final stage is the formation of cracks and disintegration
of the panels.
Replacement of roof panels in
polycarbonate and glass roofed conservatories is
straightforward. It is recommended
that replacement units conforming to the forthcoming
building regulations Document ‘L’, with
solar heat protection, are installed. Misted side window
panels are simply replaced with sealed units conforming
to Document ‘L’.
Question Five: My conservatory is looking its age,
It was fitted in 1992. There are several misted sealed
units and occasional leaks. I would like to give it
an Mot to bring it up to modern standards for year
round use since it has always been cold in winter,
and in summer impossible to use, on many days, because
of the heat and glare?
Although regular maintenance of the conservatory is
important most owners undertake none of this work,
which means that when problems occur they can be serious.
Regular maintenance, and refurbishment every ten to
fifteen years, to bring the conservatory up to modern
standards for all year round use in comfort is recommended.
Polycarbonate roof panel have a much shorter life expectancy
than glass, as little as fifteen years in some cases,
and the outer surface of the roof can become etched
and unsightly. Replacement of the roof panels alone
will go a long way towards making the conservatory
look as good as new.
Regular maintenance comprises of: Cleaning of the
glazing, external cladding and glazing beads including
the removal of adhered dirt film, moss, algae etc.
and the replacement of damaged, worn and where applicable
rotted and unsightly parts with new. NB Abrasives cleaners
of any type should not be used especially on polycarbonate
roofs, as these will damage the external ultra-violet
barrier layer that protects the roof glazing from deterioration.
The recommended 10 to 15 year refurbishment programme
1. Replacement of the roof and
side window panels with new units conforming to document ‘L’,
with solar protection to enable it to be used all year-round
as part of the house,
2. Complete inspection of the conservatory to identify
leaks, deterioration of the structure including PVC
cladding, Flashing, Glazing bar covers, Finial and
ridge areas followed by replacement and sealing as
3. Recommendations concerning heating and the sizing
of the heating system and replacement if necessary
4. Optional installation of roof vents for improved
5. Treatment of PVC, wood or other external cladding
to bring back its colour.
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 http://www.insupolycarbonate.com