GB2201701A

GB2201701A - Solar heated cavity wall

Info

Publication number: GB2201701A
Application number: GB08705358A
Authority: GB
Inventors: Roy Wormald; Mary Elizabeth Sweeney
Original assignee: Individual
Current assignee: Individual
Priority date: 1987-03-06
Filing date: 1987-03-06
Publication date: 1988-09-07
Also published as: GB8705358D0

Abstract

A new or an old, conventional cavity wall has a selective coating 2 applied to its external surface to produce high solar absorptivity but low longwave emmisivity. To this combination a suitable air gap, frame and glazing 1 is provided to protect the outer leaf. Heat produced by the absorption of solar radiation on the selectively coated surface passes by conduction through the outer leaf into the cavity. Air flowing from an inside room to the bottom of the cavity 7 is heated and exits at the top 9. A small fan 8 may be inserted into the air stream to improve the solar wall's performance. <IMAGE>

Description

SOLAR HEATED CAVITY WALL This invention relates to a solar heated cavity wall. Cavity walls are a standard form of construction in the building industry, and consist of two leaves of a building material, (such as brick, block or concrete), with a cavity in between. The leaves are often of 100 mm thickness, the cavity has in the past been usually 50 mm in width.

On sunny days the outer leaf of such a wall will be warmed by the sun, and conduct heat to the building interior. The efficiency of such heat transfer is however reduced by large heat losses from the unprotected external face.

Special solar storage walls have been built, which utilise a massive outer leaf, painted matt black, to store incident solar radiation. The outer surface has been covered by glazing to reduce the convective and radiative heat losses, and the stored heat is allowed to enter the building using thermocirculation and/or conduction. Special selective coatings of low emissivity (for long wave radiation) and high absorptivity (for solar radiation) have been used to increase the performance of walls.

According to the present invention these features are applied to a conventional cavity wall, either newly built or as a retrofit to an existing one.

To the external surface of this wall, a selective coating, a framework, and glazing is applied. A suitable air gap separates the glazing from the wall.

Heat is conducted through the outer leaf into the cavity, and air passing from an inside room, into the cavity, is heated and exits at the top of the cavity back into the building. A small fan may be installed into this air stream to improve the solar wall's performance.

A specific embodiment of the invention will now be described by way of example, and reference is made to the accompanying drawing in which: Fig. 1 shows a section of a wall.

Fig. 2 shows a wall in perspective from the front.

Fig. 3 shows a wall in perspective from the back.

The external leaf of this wall (3), is built of 102.5mm brick, and faces south. It has a selectively coated foil (2), adhering to its front surface, and an air gap of 100 mm between that surface and the single glazing of normal glass in a suitable sealed framework (1). Heat from the absorption of solar radiation passes through the wall by conduction and enters the cavity (4). This is of 50 mm thickness, and the rear leaf of the wall is built of lOOmm thick aerated concrete blocks (6). 25 mm thickness of an insulating material such as fibreglass or polystyrene foam (5) is fixed to the cavity side of the blocks. Heat losses through the rear leaf are thus very small. Air enters the cavity via small ducts (7) in the bottom of the wall, is heated and rises up the cavity, to exit through a duct at the top (9). The performance of the wall is much improved if a small fan (8) is placed in the exit duct to facilitate heat extraction. The fan can be either manually operated or activated using a differential temperature controller, which operates when the temperature at the top of the cavity exceeds that of the inside air.

Claims

1. A solar heated cavity wall, comprising a conventional cavity wall, with a selective coating material applied to the front surface of the outer leaf. This external surface is provided with an air gap, window frame and glazing. Solar radiation passing through the glazing, heats the outer leaf of the cavity wall, and passes by conduction into the cavity. Air flowing from an inside room to the bottom of the wall, through the internal cavity is heated and exits into an inside room from the top of the cavity.

2. A solar heated cavity wall, as in claim 1, where a small fan is inserted into the stream of flowing air to improve the performance of the solar wall.

Amendments to the claims have been filed as follows A A solar heated cavity wall, comprising a conventional cavity wall built from standard construction materials, with a selective coating material applied to the front surface of the outer leaf. Such a cavity wall has a thin, outer leaf of a building material, which is provided with a window frame and glazing, so that an air gap exists between the glazing and the surface covered by the selective coating. Solar radiation transmitted through the glazing, heats the outer surface of the cavity wall, this heat subsequently passing solely by conduction through the outer leaf into the cavity. Ducts are provided only in the top and bottom of the inner leaf to enable air to flow from an inside room to the bottom of the internal cavity, where after heating, it re-enters the room from the top of the cavity.