Before investing in solutions, diagnose the problem. Use this checklist to identify exactly what’s wrong — the answer usually falls into one of five categories.

Ordinary glass is transparent to short‑wave solar radiation but blocks long‑wave heat radiation from escaping. This is the greenhouse effect — and in a conservatory, it’s devastating.

Polycarbonate roofs (common on older conservatories) are particularly bad: they trap heat aggressively and degrade over time, turning opaque and losing structural integrity. Glass roofs without solar‑control coatings also cause severe overheating.

Roof orientation plays a major role. A south‑facing conservatory gets maximum sun exposure and will overheat fastest. A north‑facing conservatory is less likely to overheat but will feel colder in winter. Even well‑ventilated spaces struggle without proper solar control glass.[reference:1]

Heat escapes through the path of least resistance. In a traditional conservatory, every part of the structure is a weak point.

• Roof — the single largest area of heat loss. Polycarbonate roofs have a U‑value of roughly 3.5 W/m²K, losing heat five times faster than a modern insulated roof.
• Frames — non‑thermally‑broken aluminium frames act as thermal bridges, conducting cold directly inside. Traditional aluminium has a conductivity of 160 W/m²K.
• Glazing — single or early double glazing (U‑value 2.8–5.8) loses heat dramatically faster than high‑performance glass (0.18 W/m²K).

Condensation occurs when warm, moisture‑laden air hits a colder surface (the glass or frame). The colder the glass, the higher the risk of condensation.

Condensation is caused by a combination of:

• Poor insulation — uninsulated or poorly insulated walls and roofs create cold surfaces that attract moisture.[reference:3]
• Inadequate ventilation — without fresh air flow, humidity builds up rapidly.[reference:4]
• High humidity sources — using the conservatory as a kitchen extension increases moisture levels exponentially.[reference:5]
• Cold glass temperatures — standard double glazing has a much lower internal surface temperature than high‑performance glass.

Each gap in your conservatory’s envelope is a direct channel for cold air to enter and warm air to escape.

• Failing seals and gaskets — rubber seals degrade over time, becoming brittle and allowing air to bypass.[reference:7]
• Poor installation — gaps between window frames and the wall are common in older conservatories.
• Warped frames — timber or uPVC frames can warp, creating gaps that worsen over time.[reference:8]

A professional inspection (part of any thorough refurbishment) will identify every leak point. In many cases, seals can be replaced relatively inexpensively — but the underlying frame and glazing will still be thermally inefficient.

Leaks are most common around roof panels, gutters, and at the junction where the conservatory meets the house.

• Failed roof seals — silicone or rubber seals between roof panels degrade with age and UV exposure.
• Cracked glass or damaged panels — a single crack is enough to let water in.
• Blocked gutters and drainage — overflowing gutters can pour water down walls.
• Poor installation — inadequate sealing at the house connection is a common issue.[reference:9]

The solution depends on which of the five problems you’ve diagnosed.

🛠️ Quick Fixes (Temporary)

• Blinds and curtains — help with glare and some heat‑gain
• Dehumidifier — manages condensation symptoms, not the cause[reference:10]
• Draught excluders — reduce air infiltration
• Portable heaters — temporary warmth that costs a lot to run

🔧 Effective Upgrades

• Thermal glass upgrade — New Generation Glass (U‑value 0.18) outperforms most insulated solid walls and eliminates both overheating and excessive heat loss.
• Roof replacement — a hybrid or solid insulated roof dramatically improves thermal performance while preserving light.
• Frame replacement (thermally broken aluminium) — eliminates conductive heat loss through the frame.
• Full refurbishment — the only way to guarantee year‑round comfort is to address all failure points simultaneously.[reference:11]