What Eltham weather does to a conservatory
We ran Eltham's hourly weather for 2024 and 2025 through the same room three times, once per roof. The squares are hour by hour averages. The garden never beat 33.7°C and July averaged 18.6°C, but the polycarbonate room touched 49°C, against 37°C with panels.
A year inside a Eltham conservatory
Average room temperature, every month and hour of 2024 and 2025
- 1,461
- hours over 25°C
- 49°C
- hottest hour
- 33°C
- July, 3pm
- 1,597
- hours over 25°C
- 52°C
- hottest hour
- 35°C
- July, 3pm
- 442
- hours over 25°C
- 37°C
- hottest hour
- 25°C
- July, 3pm
Blue: heater weatherPale: comfortableAmber to plum: too warm
The hours you get back
A heater can rescue a chilly hour. Nothing cheap rescues a 31°C one. So the useful measure is how many waking hours stay at or under 25°C: in Eltham that is 3,652 a year under polycarbonate and 4,671 under an insulated panel roof, roughly 1,019 hours handed back.
The worst hours, above 30°C, fall from 685 to 67. A glass roof manages 849.
- Polycarbonate roof1,461 h too warm
- Glass roof1,597 h too warm
- Panel roof442 h too warm
Too cold (under 12°C)Chilly (12 to 17°C)Comfortable (17 to 25°C)Warm (25 to 28°C)Too hot (over 28°C)
When the heat peaks in Eltham
June is the problem month here: 53% of its waking hours top 28°C under polycarbonate, 14% under panels. Spring and early autumn matter too, when the sun is still strong but nobody expects to open the doors.
Polycarbonate roofInsulated panel roof
Winter in Eltham
Winter here bottoms out in January at an average of 4.5°C (coldest hour -5.1°C). Keeping 19°C while the room is in use costs about £388 a year in electricity under polycarbonate and £334 under the panel roof, 1,475 against 1,268 kWh.
We would not sell the roof on that difference alone. The glass walls keep losing heat either way; what changes most is that the room stops cooking in summer and a smaller heater copes in winter.
Prices for Eltham conservatory roofs
Prices in Eltham are the same as everywhere we work: the roof, not the postcode, sets them. The survey is free and the written price is fixed. See the price page for every shape, or get a guide price for your roof in about a minute.
| Shape | Small (up to 12 m²) | Medium (12 to 25 m²) | Large (over 25 m²) |
|---|---|---|---|
| Lean-to | from £3,000 | from £4,000 | from £5,000 |
| Edwardian | from £3,150 | from £4,200 | from £5,250 |
| Victorian | from £3,300 | from £4,400 | from £5,500 |
Fitting day
Plan on a single day for most Eltham roofs, usually a second for a P-shape. We take the old roof away the same day and leave the room swept. The fitting day walks through it hour by hour.
Towns near Eltham
Compare your neighbours, or see all of Greater London and the full overheating league table.