Passive Solar Design

Clay Bricks have natural thermal qualities that slow the transfer of heat through the walls of houses, thereby contributing to optimal thermal comfort. Buildings are kept cool in summer and warm in winter, resulting in low energy requirements for artificial heating and cooling.

An acceptable thermal comfort range is ultimately what the building envelope is aiming to achieve. The building interacts with the environment and transfers the environmental conditions to the interior, therefore influencing the thermal comfort experienced by the occupants, directly. Thermal comfort targets vary according to external weather conditions and the type of ventilation the building requires. Through intelligent design and using a product with high thermal mass like Clay Brick, a consistently comfortable range of temperatures can be maintained. The findings of recent independent research undertaken by WSP Green by Design on both 40m² and 130m² house types, where Clay Brick walls were compared with insulated lightweight walling and through the wall construction, confirmed that Clay Brick walled houses consistently led to lower energy requirements for heating and cooling.

Essential elements of passive solar design

Passive Solar Design buildings are constructed on the pillars of correct orientation, appropriate ventilation with windows and doors, careful use of insulation, adequate shading and most importantly, the extensive use of building materials with high thermal mass.


Buildings need to be orientated with nature and the position of the sun in mind. In the southern hemisphere the north facing side of the building gets the most sun, and rooms desired to be warmest should be positioned here, such as; bedrooms, lounges and other living areas. More functional rooms can get away with being positioned towards the cooler south facing side.


Ventilation can be optimised by utilising the natural flows of wind and air movement in relation to the location as a means of cooling the building. Using seasonal wind data it is easy to plan the positioning of openings to maximise air flow during summer and minimise it in winter.


Buildings should be well sealed, and in certain location/building-type combinations it’s important to add insulation to existing thermal mass. Insulation, in combination with thermal mass in climates like South Africa where diurnal temperature swings are pronounced, increases occupancy comfort and contributes towards reduced energy consumption.


Shading has a role to play in moderating building temperatures. By taking the 47° altitude difference in the angle of the sun between noon in summer and noon in winter, the exact necessary length of the eaves of the roof can be determined to protect the walls and windows from direct sunlight in summer, and expose them during winter.
Primer for Energy Conscious Design
– Professor Dieter Holm & Reinold Viljoen 1996

Thermal mass

South Africa is a climate that is characterised by high diurnal temperature swings – the difference in temperature between day and night – and also relatively high absolute summer temperatures. Thermal mass works particularly well in these types of climates, storing heat energy during the day and releasing it at night. Your choice of building material can play an instrumental role in regulating internal temperatures. A high thermal mass product like Clay Brick, especially when used in a cavity wall for example, can delay the transfer of heat up to 8 hours, reducing peak daytime temperatures and preserving the warmth well after the sun goes down.

Life cycle of clay brick buildings

Clay Bricks boast an extensive life span exceeding 100 years. The overall life cycle of a Clay Brick building is measured by its impact on the environment from the early stages of production; from the sourcing of raw materials to producing the end product, construction of the building and its in-use phase up to final demolition. Besides the energy efficiency gains of thermal mass, Clay Bricks are inert, non-toxic, highly durable, long lasting and require very little maintenance. They are also fully recyclable. Clay Bricks also allow for flexibility in design and layout at any time during construction of the building and its life.

Sustainability vs. affordability

Clay Bricks have an inherent thermal mass, which means, when used in accordance with proper sustainable design principles they retain much of the energy they absorb. This cuts down on a building’s need for mechanical heating and cooling. Recent studies undertaken by WSP Green by Design confirm that Clay Brick walls provide the lowest life cycle energy costs and lowest life cycle costs over a 50 year life cycle. The long term benefits of building with Clay Bricks, both financially and environmentally are irrefutable.

Role in uplifting communities

Genuine Clay Bricks have been playing a vital role since earliest house construction in South Africa. The phenomenal structural integrity and longevity of Clay Brick means that our homes are of substance and built to last for many generations, and in a very real sense adds to the investment value and upliftment of sustainable communities. Clay Brick in housing is not only a pillar of our great history, but will also be a pillar of our greater future.