The Equatorial Observatory, Penllergare is a Grade II* listed building in the Swansea local planning authority area, Wales. First listed on 30 April 2002. A C20 Observatory, laboratory.
The Equatorial Observatory, Penllergare
- WRENN ID
- waning-banister-swallow
- Grade
- II*
- Local Planning Authority
- Swansea
- Constituency
- Gower MP: Tonia Antoniazzi (Lab)
- Country
- Wales
- Date first listed
- 30 April 2002
- Type
- Observatory, laboratory
- Address
- The Equatorial Observatory, Penllergare, Penbwl Wood, Penllergaer
- OS grid reference
- SS 622 990
- Coordinates
- 51.67369, -3.99339
- Source
- Cadw listing
Description
The Equatorial Observatory in Penllergare is a Grade II* listed building that serves as both an observatory and a laboratory. The observatory features a cylindrical tower made of tolled squared stone, topped with a 20th-century metal-clad cylinder. This windowless tower has small square recesses near the base and an ogee cornice that shows signs of erosion and has been patched with cement.
The laboratory is a single-storey structure built in a neo-Jacobean style using yellow patent blocks, which are larger than standard bricks. It has a slate roof that is hidden behind a parapet. The stone plinth supports terracotta-block walls, and the parapet features a central neo-Jacobean gable that was rebuilt in imitation blocks in 1981. There is one window on the north side, which has a 20th-century cross-window that may have been placed in a former door opening. The window surround is chamfered with terracotta block voussoirs. The south side has a similar window to the right and a central door, both with matching chamfered surrounds and voussoirs, featuring 20th-century door and window fittings.
The interior of the observatory is not accessible, while the laboratory consists of a single room with terracotta block walls and a fireplace located on the right end wall.
Local climate
The Equatorial Observatory, Penllergare sits in one of the wettest parts of the UK, with an average of 1,420 mm of rain a year. This makes it wetter than 98% of listed buildings in the UK. Its exposure to wind-driven rain is greater than that of 98% of listed buildings.
It experiences an average of 16 freeze-thaw cycles a year, fewer than 84% of listed buildings. Of these, 6 follow at least 1 mm of rain in the preceding 48 hours. Average temperatures at this location have risen by 0.3°C per decade since 1991.
Averages for 1991–2020; temperature trend 1991–2025. Figures describe the wider area (a grid cell of roughly 10 km), not the individual site. Contains modified Copernicus Climate Change Service information 2026.
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- Detailed attributes — period, style, materials, features
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