Are Orangeries and Conservatories cold in the winter?

14 Nov

Warmth is a big concern during the winter, especially in extensions. A good extension with quality materials and glazing that meet current standards should be comfortable all year round, not just in summer or winter.

In fact, orangeries can be incredibly warm and welcoming spaces over the winter, and still feel comfortably cool over the summer. But there are several important factors that contribute to their year-round comfort, even in the coldest of winters.

So why do people worry that orangeries or conservatories are cold in the winter? It’s likely down to the poor reputation of old-fashioned glazed rooms, that were unusable for 6 months of the year. But over the last 30 years we’ve seen great advancements in glazing technology and access to superior materials that have enabled garden rooms to be just as warm as any other room in your house – even during the winter.

Orangery or conservatory on a cold winter morning

Some of the reasons why orangeries or conservatories are not cold in winter

Insulation

It goes without saying, if you want to hold as much heat inside your home as possible, you will need insulation. Orangeries in particular feature dwarf walls, built columns and a flat roof, all of which can be fully insulated and help to reduce warm air from escaping. In addition, high performing weather seals should be used across all doors and windows to prevent the cold air from outside from entering your home.

Thermally efficient windows and doors

With a large portion of an orangery or conservatory being glazed, it’s important to also minimise the heat loss through the glazed panes. That’s where an understanding of U-values comes in. U-values are calculated by finding the sum of thermal resistance, the lower the U-value the better your glass will perform in the winter as the glass allows a low amount of heat transference. The same principles can also be applied during the summer, with less warm air being transferred from the warm air outside, into your home.

Modern living room with skylight, fireplace, and cozy seating—never cold like traditional orangeries and conservatories.

Thermally efficient roof lanterns and glazed rooves

Lanterns are brilliant to not only bring in a great deal of natural light, but they are also thermally efficient. We use toughened, argon filled, 4-16-4 units with warm edge spacer bars as standard. What does all that mean exactly? It means that each toughened pane experiences minimal heat loss throughout the winter and each edge of the sealed glazed units are kept apart to prevent cold bridging – a cold bridge is a gap between two insulated parts. This gap is colder than the surrounding areas and can cause a build-up of condensation. Leading to heat loss, mould growth, deterioration of the building, and making orangeries and conservatories feel cold.

Bright living room with large windows, skylights, and orangeries—never cold, with views of the patio and lush garden beyond.

Underfloor heating

When there is a large portion of glazing surrounding the room, there may be little opportunity to hang radiators. Which is why in the past, conservatories had poor heating control. Becoming the only room within your home that doesn’t receive the same central heating. Underfloor heating offers a superior solution, not only warming the tiled floor underfoot. But also warming the room evenly in its entirety.

Cozy living room with two brown armchairs, ottoman, large windows like orangeries—never cold with warm lighting.

How important are U-values for glass to ensure your orangeries or conservatories are not cold in the winter?

The first thing to note is that not all glazing is tested the same for its thermal performance. Each and every door or window from our orangeries or conservatories are independently tested for their U-value in their entirety. To give the most accurate performance results possible for the whole product. Glazing and frame.

Comparatively some companies prefer to only test the centre pane which can produce misleading results. This is down to how glass transfers heat. The centre of the pane is the most thermally efficient area of the entire glazed unit. Gradually decreasing around the edges where all glass will experience some loss, until you reach the surrounding framework where there will likely be heat loss. If the U-value of a window is only tested on the centre or the glass pane, your windows and doors could experience a great deal more heat loss than you may have expected over the winter.

Large house with a sunroom and cold patches of snow, featuring orangeries, leafless trees, and a narrow garden pond.

Once you understand these different methods of measuring the U-values, they can provide a useful tool for judging how well your dream orangery or conservatory will fare over the winter. Building regulations for the current* standard for energy-efficient glazing set a maximum U-value of 1.4W/(m²K) for new windows and glazed doors.

When tested by an independent body, our U-values range from 1.4 as standard up to 1.1 for triple glazing. Westbury meets that standard as a baseline and goes well beyond it if you need or want the extra performance.

A ground-floor conservatory or orangery under 30m² is exempt from the energy efficiency rules. That’s the case, provided it’s thermally separated from the house by a wall, door, or window that meets the 1.4 standard, and the home’s heating system doesn’t extend into the new room. If the extension is larger, or on an upper floor, or heated as part of the house, it has to meet the same standards as the rest of the property.

*Correct as of August 2026, under Approved Document L, Volume 1: Dwellings (2021 edition incorporating 2023 amendments). Check gov.uk for the current version before relying on this for a live project, since it’s revised periodically, and a further edition is already due to come into force on 24 March 2027.

_{*Time of writing 11/01/22}

Frequently Asked Questions

Are conservatories cold?

Conservatories have a fully glazed roof and two or three glazed walls, so there’s very little solid material to hold in heat, making them susceptible to cold. This is because glass loses heat faster than an insulated wall or roof, regardless of how good the glazing is. Because of this, conservatories tend to overheat during the warmer months of the year.

Are orangeries cold in winter?

By design, an orangery has a solid perimeter roof and brick or masonry walls, with glazing concentrated in a roof lantern at the centre. A well-specified orangery will be able to remain well-regulated throughout the year, comfortably warm in winter and balancing heat in summer.

How do you keep an orangery warm?

Keeping an orangery warm is down to its design. The walls and roof sections need to be insulated to the same standards as the house it’s attached to, and the glazing should be double or triple by standard. Where possible, installing underfloor heating rather than radiators keeps heat at the level where people are, rather than pooling underneath the roof lantern. Finally, you should ensure the room is properly sealed from any unheated part of the house.

Are modern conservatories warm in winter?

Modern conservatories are warmer than ones built in the 80s or 90s due to the change in glazing standards. However, a fully glazed roof and walls will always lose heat faster than a solid, insulated one, which is what separates a conservatory from a garden room or orangery.

Why is my conservatory so cold in winter?

If your conservatory is too cold in winter, this could be because it’s an older structure or it has single glazing. Other common factors could indicate poor insulation in the roof, no proper heating system, or poor sealing.