PDI Design Inc. Wednesday 06 Jul 2011

The Solar Lounger is a solar heated thermal chair and bed. It is made with inexpensive, recycled materials and acts both as furniture and a passive thermal device.

The project was inspired by a winter visit to townships in South Africa. There the desert climate produces extreme temperatures and difficult conditions for unheated households when night time temperatures drop below freezing.

Township housing reflects the resourcefulness of the residents who utilize whatever materials are available to build their homes. This project was created in the same spirit. The basic thermal principles of the design follow indigenous methods of heating and cooling in this climate.

For thousands of years the Basarwa tribe in Botswana have cooled themselves by resting in shallow holes dug in the sand. The sand pulls the heat from their bodies providing relief from the sun. At night, they light a fire in the sand and stay warm by sleeping where the sand has absorbed the heat, benefiting from the thermal mass.

The thermal chair and bed use simple, inexpensive materials: a garden hose, recycled soda cans and reflective snack bags, wood framing, twine and sand. Direct sunlight heats the water in the hose which rises in temperature, and the heat is absorbed by the sand above. At night the solar collector is brought indoors and reversed with the thermal mass placed downward forming a heat-radiating back rest or bed. In the overheating period of the summer the process can be reversed; the damp sand is placed outdoors at night and brought indoors during the day to provide passive cooling.

The Solar Lounger utilizes inexpensive and readily available materials, is easy to build for personal use or low-cost manufacturing and uses passive solar energy and simple thermal mass principles. The design is under development with prototypes currently being tested.