One of the most efficient improvements that can be done to the brickmaking process is to make sure the bricks are completely dry before firing. If the bricks contain moisture, fuel will be wasted drying bricks to remove moisture before they can be fired.
During kiln construction, if the bricks are too close together, air circulation will be poor. Larger spaces between bricks will help the clamp heat more efficiently, and will allow steam to leave the kiln more completely. Allowing steam to leave the brick will reduce the amount of condensation that can get into a brick and increase strength. The improved circulation will reduce the amount of fuel used and time spent firing the bricks.
After the clamp is constructed, mud and broken bricks should be used to insulate the sides and top of the structure. A good insulation of the clamp will help reduce the amount of wood used by keeping more heat in the kiln as well as heating the outer sections of the clamp more efficiently. This will result in a more thorough firing of all the bricks.
There are many alternative sources of fuel used to fire a kiln that can replace firewood, which can be helpful in areas where firewood is already scarce. Some of these alternatives are:
There are different ways to use these alternative fuels, also. Finer fuels such as sawdust, husks and coal powder can be added directly to the clay mix. The fuel will burn completely within the clamp. This will also help reduce the chances of cracking during the drying process. Another way to use the alternative fuel is to throw it directly into the fuel tunnels. This is called charging, and the fuel will burn and release a sudden burst of high energy. Other fuels, such as coconut shells or coal, can be mixed with the fuel used for charging.
From Brick by Brick: Participatory Technology Development in Brickmaking by Kelvin Mason
More bricks can fit into a bigger kiln relative to surface area than a smaller kiln. The surface of the kiln is where the heat is lost and the volume to surface area ratio is higher for a larger kiln.
This is the same concept as size: the square kiln will have a higher volume to surface area ratio than the rectangular kiln. The side walls on a rectangular kiln lose more heat than the smaller walls.
As previously mentioned, thicker scoving (the mud used to insulate) will reduce heat losses.
Less heat is lost when fuel is placed next to bricks, so one technique includes adding the fuels to the clay mix. The fuels need to be fine, or when fired they will leave voids.
When firing a clamp, extra energy is used in pre-heating a brick. A continuous kiln will have a continuous heat source, so green bricks are heated from the previous firing cycle or by secondary heat. Continuous kilns may not work for smaller brickmakers since the kilns need to be bigger for the process. However, larger brickmakers can benefit from a lot of saved energy using a continuous kiln.
As previously mentioned, fuel will be wasted if the energy released is used for drying green bricks instead of firing them.
This concept is similar to drying bricks: fuel will burn more efficiently and give off more energy if it is dry and does not waste energy on drying other fuel.
Clamps should not rise in temperature too fast or a lot of heat will be lost and bricks may be damaged. The first part of the firing process dries bricks and they cannot use the heat needed to fire until dry. Bricks far away from the fires may also not vitrify to the same extent as those near the fire if the temperature rises too fast. The flow of air also impacts the temperature: air flow will cool a kiln and waste energy.
Record keeping of the amount of fuel or energy used will allow the brickmakers to see if money and time are being saved with different trial techniques. This is important if extra effort is needed to enact an energy-saving technique.
Alternative fuels can include coal, maize cobs or rice husks, straw or animal dung. The costs may be reduced for an equal or increased energy.