Orangery vs. Conservatory Glazing: A UK Homeowner's Guide

When planning a home extension in the UK, two popular choices often come to mind: the orangery and the conservatory. While both offer a fantastic way to expand living space and bring more natural light into your home, their construction, aesthetics, and crucially, their glazing specifications, differ significantly. Understanding these differences is vital for making an informed decision that aligns with your budget, design preferences, and thermal performance requirements.

This comprehensive guide will delve into the world of orangery and conservatory glazing, providing UK homeowners with the technical knowledge, regulatory insights, and practical considerations needed to choose the right option for their property.

Understanding the Basics: Orangery vs. Conservatory

Before we dive into the specifics of glazing, it's important to clarify the fundamental distinctions between an orangery and a conservatory, as these impact the glazing choices and regulatory compliance.

What is a Conservatory?

Traditionally, a conservatory is characterised by a high proportion of glazing in its walls and roof. It is often seen as an extension that is distinct from the main house, primarily designed to maximise natural light and offer a connection to the garden. Historically, conservatories were exempt from certain Building Regulations, provided they met specific criteria:

• Must be at ground level.
• Must have a floor area of less than 30m².
• Must be thermally separated from the main dwelling by external quality doors or walls.
• Must have an independent heating system with separate controls.
• At least 75% of the roof area and 50% of the wall area must be glazed.

However, modern conservatories, especially those designed as integrated living spaces, often seek to comply with Building Regulations to be considered a 'habitable room', which changes the glazing requirements considerably.

What is an Orangery?

An orangery, by contrast, typically features more brickwork or solid wall construction than a conservatory. It usually incorporates a flat roof perimeter with a glazed lantern or rooflight at its centre. This design provides a more substantial, 'room-like' feel, blending seamlessly with the existing architecture of the home. Orangeries are generally designed to be an integral part of the main living space, meaning they almost always need to comply fully with UK Building Regulations, including stringent thermal performance standards.

Glazing Specifications and Thermal Performance

The thermal performance of glazing is measured by its U-value, expressed in Watts per square metre Kelvin (W/m²K). A lower U-value indicates better insulation and less heat loss. This is a critical factor for comfort, energy efficiency, and compliance with Building Regulations.

Conservatory Glazing

For traditional conservatories that are thermally separated from the main dwelling and meet the exemption criteria, the glazing requirements are less stringent. However, to ensure comfort and energy efficiency, homeowners often opt for high-performance glazing anyway.

• Double Glazing: Standard double glazing typically achieves U-values between 1.6 and 2.8 W/m²K.
• Low-E Glass: Incorporating a low-emissivity (Low-E) coating on one of the glass panes significantly improves thermal performance by reflecting heat back into the room. This can reduce U-values to around 1.2-1.4 W/m²K.
• Argon Gas Filling: Replacing the air in the gap between panes with inert gases like argon further reduces heat transfer, improving U-values to approximately 1.0-1.2 W/m²K.
• Solar Control Glass: For conservatories that receive a lot of direct sunlight, solar control coatings can help reduce overheating in summer by reflecting a percentage of solar energy, while still allowing light in.
• Self-Cleaning Glass: A practical option for conservatory roofs, these coatings use sunlight to break down organic dirt, which is then washed away by rain.

Orangery Glazing

Orangeries, being more integrated into the home, must meet the same rigorous thermal performance standards as any new extension under UK Building Regulations Part L (Conservation of Fuel and Power). This means all glazing, including the roof lantern, must achieve specific U-values.

• Walls (Windows & Doors): For new build and extensions, the maximum U-value for windows and doors is 1.2 W/m²K. For replacement windows/doors, it's 1.4 W/m²K. Orangery wall glazing must meet these standards.
• Roof Lanterns/Glazed Roofs: While there isn't a single prescriptive U-value for glazed roofs, the overall extension must meet an average U-value for its thermal envelope. High-performance double or even triple glazing is often necessary for roof lanterns to contribute positively to this overall average. U-values of 1.0 W/m²K or lower are desirable for roof glazing.
• Triple Glazing: Increasingly popular for orangeries, triple glazing offers superior thermal performance, achieving U-values as low as 0.6-0.8 W/m²K, significantly enhancing energy efficiency and comfort.
• Warm Edge Spacers: These non-metallic spacers between glass panes reduce heat loss at the edges of the sealed unit, improving the overall U-value.

UK Building Regulations and Planning Permission

Navigating UK Building Regulations and Planning Permission is crucial for any extension project.

Planning Permission

Many conservatories and orangeries can be built under 'Permitted Development' rights, meaning you don't need to apply for full planning permission. However, strict limits apply regarding size, height, proximity to boundaries, and materials. For instance, the extension must not cover more than half the area of land around the original house. If your proposed extension exceeds these limits, or if your property is in a conservation area or is listed, you will almost certainly need planning permission.

Building Regulations

This is where the distinction between conservatories and orangeries becomes most apparent regarding glazing.

• Exempt Conservatories: As mentioned, a traditional conservatory that is thermally separated from the main house and meets other criteria (under 30m², independent heating, etc.) is generally exempt from Building Regulations. However, this exemption means it cannot be considered a 'habitable room' for regulatory purposes, and its thermal performance might be lower than an integrated extension.
• Integrated Conservatories & Orangeries: If your conservatory or orangery is designed to be an integral part of your home (e.g., open-plan access to the main living space, shared heating system), it must comply fully with Building Regulations. This includes meeting stringent U-value requirements for walls, floors, roofs, and all glazing.

Current UK Building Regulations Part L (2022 England) U-value requirements for new extensions:

Element	Maximum U-value (W/m²K)
Walls (New Build & Extensions)	0.18
Floors	0.18
Roofs	0.15
Windows/Doors (New Build)	1.2
Windows/Doors (Replacement)	1.4
Party Walls	0.0

Meeting these U-values for an orangery, particularly for the roof lantern and large glazed sections, often requires high-specification double or triple glazing with low-E coatings and inert gas filling. Failure to comply with Building Regulations could affect the sale of your property in the future, and it is advisable to consult with your local Building Control body or a professional architect/designer early in your project.

Design and Aesthetic Considerations

Beyond technical performance, the visual impact and design integration are paramount.

Conservatory Aesthetics

Conservatories typically offer a very light and airy feel, with minimal solid structure. This maximises views and creates a strong connection to the outdoors. The choice of frame material (uPVC, aluminium, timber) and glass type (clear, tinted, patterned) can influence the overall look. Modern conservatories can still achieve excellent thermal performance, blurring the lines with orangeries.

Orangery Aesthetics

Orangeries provide a more substantial and architectural presence. The combination of solid walls with large glazed elements and a prominent roof lantern creates a grander, more permanent structure. The roof lantern itself becomes a key design feature, allowing light to flood the central space. The greater proportion of solid walls offers more privacy and opportunities for integrating the extension with the main house's interior design, such as hanging artwork or installing built-in furniture.

Pros and Cons of Each Glazing Approach

Choosing the Right Glazing for Your Project

The decision between an orangery and a conservatory, and consequently the glazing choices, depends on several factors:

• Intended Use: Will it be a sunroom, dining room, living area, or home office? If it's a year-round habitable space, an orangery with high-performance glazing is usually the better choice.
• Budget: Orangeries typically have a higher upfront cost due to their construction and glazing specifications.
• Aesthetics: Do you prefer a light, glass-dominant structure or a more substantial, architecturally integrated extension?
• Energy Efficiency: For maximum thermal performance and lower heating bills, an orangery designed to Building Regulations standards with high-spec glazing is superior.
• Planning & Regulations: Always check with your local authority regarding planning permission and Building Control requirements specific to your property and proposed design.

Ultimately, both orangeries and conservatories offer unique benefits. The key is to understand how their construction and glazing specifications impact their performance, appearance, and compliance with UK standards. Investing in high-quality, thermally efficient glazing, regardless of your choice, will significantly enhance comfort, reduce energy costs, and add value to your home.

For expert advice on bespoke glazing solutions for your orangery or conservatory project, consider consulting with specialists like Shard AG. Our team can guide you through the technical specifications, regulatory requirements, and design options to create a stunning and energy-efficient extension tailored to your home.