Conservatory Glass | Richmond Oak Conservatories Limited
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Conservatory Glass

When selecting the conservatory glass & glazing for a conservatory, glass is usually a much better option than cheap polycarbonate alternatives that can become opaque and marked over time.


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What You Need to Know about Glass

It doesn’t matter whether it is manufactured from Timber, Aluminium or PVC, or whether we call it a Conservatory, Orangery or Garden Room, the most important factors concerning the use of your glazed extension are the specifications of the glass used and ventilation. Richmond Oak Clients can expect only the top glazing specifications. Here we are concerned with the glass type.

Most people are still of the belief that a structure with a lot of glass, in the roof or frames, will be too Hot in the Summer and too Cold in the Winter. This was true of most conservatories prior to 2000, when Solar Control glass was not readily available in the domestic market and a high proportion of conservatories had polycarbonate sheet roofing or standard clear glass, which could be slightly improved upon by bronze anti-sun glass. However, the latter was not terribly efficient and significantly reduced the light with an orange glow to the interior.

Richmond Oak Conservatory Glass

We are going to discuss the benefits of modern glass, which will provide a comfortable environment and enable use of a conservatory all year around. However, it is important to understand that many Companies and their representatives rely on the average customer’s lack of knowledge and sell low cost glass of inferior specifications, which are not ‘fit for purpose’ and will make the conservatory unfit for use for a large percentage of the year.

The correct toughened glass is strong and long lasting, allowing a clear view of your garden and the views beyond, as well as plenty of daylight into the interior of the conservatory and the room behind.

Unless a full Building Regulations project, Conservatory Glass is only covered by Building Regulations Part N (Safety Glass). Your conservatory designer or builder should be familiar with these and how to choose the correct glass for different places in the conservatory.

To be energy efficient and keep your heating bills low, you will need to choose glazing with the best glass u-values (heat loss values), in combination with other types of glass described here.

Heat reflective glass also known as Energy Efficient Glass, will reduce the amount of heat loss from the conservatory and glare from the sun. There are two aspects to heat reflection… Heat deflection on a hot day (Solar control glass) and heat retention on a cold day (Low emissivity glass, typically known as Low-E)

Safety Glass

Toughened safety glass is typically used in conservatories, as it is very strong and 30% lighter in weight than laminated glass.

Standard 6.4mm Laminated glass unlike toughened glass will, when hit with force, crack rather than smash into tiny pieces. Laminated glass is vulnerable to cracking as, unlike 4mm toughened, a laminated pane is two sheets of thinner, non-toughened, 3mm glass with a 3.8mm plastic interlayer.

Keeping the Heat In on a Cold Day

Glass U–Values are a measure of the rate of heat loss through different types of glass. You should choose the lowest U–Value as possible as this means less heat will escape from your conservatory, reducing your heating bills, making your glazed extension more energy efficient and comfortable during cold weather.

In simple terms, for comparative purposes, U–Values are calculated as a measurement of the amount of heat lost in Kilowatts, through one square metre of glass per hour.

Modern double glazing has a Low Emissivity (Low-E) invisible, metallic coating on one or more of its inner surfaces. This became mandatory on windows fitted to a home in 2002, but to this day, unless the project is subject to building regulations certification, there is absolutely no requirement to even have double glazing, let alone special coatings.

To get some idea of glass efficiency, these are the typical U–values for different types of glass:

  • Single–glazing 5.8
  • Double–glazing 3.0 without gas fill
  • Triple–glazing 2.2 without gas fill
  • Double–glazing with low–e hard coating 1.6 to 1.7
  • Double–glazing with low–e hard coating and Argon filled 1.2 to 1.3
  • Double–glazing with low–e soft coating and Argon filled 1.1 to 1.2
  • Triple–glazing with multiple low–e coatings and Argon filled 0.8
  • Triple–glazing with multiple low–e coatings and Krypton or Xenon filled 0.4
  • Double Glazed Tinted Solar Control with low-e coating and Argon filled 1.2
  • Celsius Clear™ Solar Control Glass with low-e coating and Argon filled 1.0
  • Celsius Elite™ Blue Tint Solar Control Glass with multiple low-e coating and Argon filled 0.9
Richmond Oak - Perfect All Year Round

PLEASE NOTE: Generally, the gap size needs to be a minimum of 16mm for optimum efficiency. Therefore, an Argon gas filled unit a triple glazed unit needs to be 44mm thick. Smaller gap sizes can reduce the effectiveness of a triple glazed unit below that of a top specification double glazed unit.

There will be a point at which the investment in better rated glass may not be cost-effective, this will depend on the total area of glass, your current and predicted energy costs, as well as how much time you plan to spend in your conservatory when the weather is colder.

If you are planning a north-facing conservatory that receives less direct sunlight than conservatories positioned elsewhere, selecting the best U-value glass will be very important. A knowledgeable glazing or conservatory consultant should be able to help you with these calculations.

Warm In The Winter

Keeping the Heat Out on a Hot Day

Solar Control Glass

For most glazed extensions provided by Richmond Oak we recommend the soft Blue Tint, Celsius Elite™ Solar Control Glass for the Roof, and Celsius Clear™ Solar Control Glass in the Frames. We recommend Celsius Clear™ in the roof if predominantly, east or north facing, or if the customer does artwork in the conservatory, where tinted glass will affect colours.

Solar Control Glass is designed to absorb and deflect heat off the glass and keep it out of the glazed extension. It does this by use of coatings and colour of the glass. Suffice to say that you should opt for glass that has the highest heat deflection offered.

For the Roof:

Richmond Oak recommends Celsius Elite™, soft blue tint, solar control glass for the roof as, at the time of writing, not only does it have a 10% greater heat retention efficiency on a cold day than any other double glazed unit available, at 83% heat reflection, it equals the maximum heat deflection of the best alternative. Currently the most recent upgrade of Pilkington Active Blue roof glass only reflects 69%, making Celsius Elite™ over 20% more efficient. It also has a uv light filterage of 94%, keeping out harmful uv light, which causes fading and damage to furnishing and floors.

For the Frames:

Richmond Oak recommends Celsius Clear™ for the frames, especially on South and West facing glazing, where it’s 58% heat reflection on a hot day keeps the room far cooler. But we also recommend it on North and East facing glazing, because its 1.0 u-value makes it 17% more efficient than typical soft coat non-solar control glass, keeping the heat in on a cold day. It also filters out 73% of uv light.

Cool In The Summer

Leaded Conservatory Glass

Leaded glass, also known as Leaded Lights is a throwback to the time when all glass was hand cast and thus only available in small pieces. These pieces would then cut to a diamond or rectangular shape and joined together by lead to make a single window. Coloured/Stained glass is made in the same way.

Using leaded glass can help you receive Planning Permission for a conservatory being attached to Listed Building or one in a Conservation Area.

Modern leaded glass is not made using the same time consuming process of joining small pieces of glass together. Instead, lead strips are inserted both inside and outside of one of the panes of a double–glazed unit. A disadvantage can be the lead does not acquire a natural patina as it is not exposed to the elements and stays bright and shiny.

Richmond Oak can overcome this problem by specifying the lead strips to be aged before being inserted into the double–glazed unit. We call this Antique Lead.

Georgians Bars

If you own a Georgian period property, it will probably have windows made up from Georgian Bars. Georgian windows are most typically made up of a number of panes.

It is possible to make Georgian Bar double–glazed windows for a conservatory with multiple panes, but these will be more expensive than single panes of glass due to extra time and materials needed to make and install them. Each unit requires 8 mitres to cut and fit each side. So just an eight pane window requires 128 mitres.

There are three ways of providing Georgian Bars:​

  • A Bar inserted between the panes of the glass double glazed unit. This is the least costly and used mainly in PVC conservatories.
  • Astragal bars – where an imitation Georgian bar is adhered to the glass either side of the double-glazed unit and a further imitation spacer bar is inserted between the glass, so that the effect is of individual panes. This method is particularly useful when requiring narrow Georgian bars and if done properly is indistinguishable from individual glazed panes.
  • Individually glazed panes of glass within the Georgian Bars. Because of good glazing practice, it is not practical to provide this method with bars much less than 44mm wide, without using special slim-line, narrow gap units. Richmond Oak will not provide slim-line units, as they are extremely expensive and have a poor track-record of failing.

Satin Privacy & Obscured Glass

Satin Privacy glass can be provided on the sides or roof of a conservatory if privacy is an issue and you are overlooked by neighbours, or passing traffic. It is particularly useful when coupled with solar control glass, when used in the roof of a conservatory, if it is overlooked from upper windows.

You can choose glass in a variety of patterns and tints and can be etched with a sandblaster in different finishes. If single glazed, the patterned side of the glass needs to be on the inside of the conservatory so that dirt and grime can easily be removed from the flat outward facing side. In double–glazed units both the inside and outside can be flat, with the patterned side in the middle of the sandwich.

Curved Conservatory Glass

Curved 3D shaped glass is sometimes found in late-Victorian and Art Deco architecture. If you own a home from this period and wish your conservatory to harmonise with it, you may need to specify curved glass for some areas of the conservatory. This will be particularly important if you need to apply for Planning Permission for a Listed Building, or one in a Conservation Area, having this type of glass.

Curved glass can be made in laminated or toughened safety glass, in single as well as double–glazed units. It is also possible to have curved glass units in Heat Reflective Glass, but the tint may not be applied if you apply for Planning Permission for a period home. Curved glass is very expensive.

The Differences between Self-Clean and Easy Clean Glass

Self–cleaning glass or Easy Clean glass will allow the conservatory to stay cleaner for a longer period than untreated glass. There is actually no such thing as ‘Self-Cleaning’ glass and we are surprised that the Advertising Standards Authority hasn’t barred the expression. With both specifications of glass, water such as rain is required to keep the glass clean. Both types of glass finish assist in improving the cleanliness of the glass and on balance, Richmond Oak recommends the Easy Clean finished used on Celsius glass.

The following provides a comparison between Self-Cleaning and Easy Clean glass.

Self-Cleaning Glass
(Titanium Dioxide Coatings)

Easy Clean
(ClearShield Non-Stick Surface Technology)

Is the Technology available today?

Self-Cleaning: Yes

Easy Clean: Yes

Hydrophobic or Hydrophilic glass?

Self-Cleaning: Is hydrophilic and causes it to sheet off the surface preventing droplet formation. This ensures loose particles (dust/dirt) are washed away easily during normal rainfall. It is also Photocatalytic – UV radiation causes the coating to oxidise dirt or organic deposits loosening them from the glass surface.

Easy Clean: Is Hydrophobic. Untreated glass attracts water and holds moisture, which over time starts the corrosion process. Moisture damages and obscures the glass. The hydrophobic Easy-Clean system prevents the retention of water in the glass pores and prevents contamination of both organic and inorganic. It also protects against corrosion, staining and discolouration of the glass.

Does the technology chemically bond to the surface of the glass?

Self-Cleaning: NO

Easy Clean: YES – Easy-Clean is applied during the manufacturing stage and left to chemically bond, becoming an integral part of the glass surface.

Is the technology effective for both organic and inorganic contamination?

Self-Cleaning: NO – Technical information specifies Self Clean removes only organic dirt.

Easy Clean: YES -Easy-Clean protects against bonding of organic and inorganic contaminants, therefore making it easier to clean, resisting staining and discolouration.

Does the technology provide protection during construction?

Self-Cleaning: NO – Manufacturers advise protecting against the glass during construction to avoid damaging the coating.

Easy Clean: YES – leaving the excess polymer on the surface of the glass provides an extra protection against contaminants during construction.

Is the technology compatible with silicone sealants?

Self-Cleaning: NO

Easy Clean: YES – There have been many approvals obtained from sealant manufacturers for product compatibility with Easy-Clean glass.

Does the technology perform in all types of environments?

Self-Cleaning: NO – Manufacturers in-house tests have mirrored real life experience but there is not enough information to date, to draw a conclusion.

Easy Clean: YES – Easy-Clean has performed successfully under many types of environments over more than 25 years

Has the technology been proven in the field?

Self-Cleaning: LIMITED – Isolated field trials in a restricted environment.

Easy Clean: YES - Guidelines for the durability and confirmation of performance are based on 20 years of successful field experience.

Aftercare required?

Self-Cleaning: YES – Requires cleaning if environmental conditions are not ideal.

Easy Clean: YES – Unique and complete system for maintenance of glass to ensure maximum performance

Other?

Self-Cleaning: Very susceptible to construction contamination. Does not remove contaminants. No silicone sealants or oils to be used with the system. Cannot be applied on site – therefore any damage to the coating requires that the glass has to be replaced.

Easy Clean: UV stable. Does not migrate onto other surfaces and Does not bond to other surfaces than glass.

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Richmond Oak Conservatories Buyers Guide

Need a little more information?

To help you with your buying decision of your bespoke hardwood conservatory or orangery, we have put together the Richmond Oak Buyers Guide.

"What you need to know when planning to Improve Your Home with a Conservatory or Orangery".