Keeping your house warm in winter and cool in summer

Best choice

Gas heaters are very effective and quickly warm up a whole room. They are the best appliance when considering cost, health and safety. When using gas it is important that the room is well ventilated. This requires gas bottles and appliances and easy refilling to be in place. Gas heaters are more expensive than other options, but long-lasting. The electric oil heater is more effective than the bar heater, but more expensive to buy. Coal, wood and paraffin are easily available and can be used both for cooking and heating, making them attractive options, but with health and safety problems.

Temperature tips

  • Do not use the oven or stove plate to warm your house – a (gas) heater is more effective and much cheaper to use.
     
  • Seal doors and windows from draughts – make a door ‘worm’ out of scrap material. Tightly sew a long sausage (10 cm diameter – about the diameter of a cooldrink can). Stuff the ‘worm’ with sand. Place the ‘worm’ on the inside of the door at the bottom. This will keep the wind and draughts out.

Note: draughts should only be blocked if the house is adequately ventilated.

Designing an energy-efficient house

Reduce up to 70% of your total household energy needs through simple design principles that reduce lighting, heating and cooling needs. This is known as passive solar design.

  • Orientate your house to the north for light and sunshine.
     
  • As the northern side of your house receives the most sun, the roof overhang should be longer (at least 40 cm to 60 cm) in length. Windows will be shaded in summer when the sun is high, while allowing the sun’s rays through the windows in winter when the angle of the sun is low.
     
  • Window shutters, awnings or screens shade rooms by keeping the hot sun rays out during summer.
     
  • A skylight in the roof allows natural light into the house on sunny days and eliminates the use of artificial lighting. Make sure that the sloping glass of the skylight faces north.
     
  • Natural materials (stone, timber, thatch and clay), often obtained locally, are most suited to keeping the home cool in summer and warm in winter. Mud bricks are an excellent source of insulation.
     
  • Floors made out of brick or concrete maintain comfortable temperatures in your house as they are good at absorbing heat during the day and releasing this slowly at night. These floors should not be covered with carpets as a concrete floor absorbs more heat than a floor covered by carpeting.
     
  • Heat loss is ten times faster through glass windows than through insulated walls, so open the curtains during the day (let in the natural light and heat) and close them at night (to keep in the heat).
     
  • Grow a deciduous creeper or tree over a veranda or yard. During summer, these leafy plants shade your house. When the leaves are lost during autumn, the bare tree lets the rays into the house (through the windows) during the colder months.
     
  • A tin roof loses a lot of heat during the winter and gets very hot in summer. Insulate the roof and paint it white (refects light and is therefore cooler) or use aluminium or other roofing materials.
     
  • A ceiling and insulation in a small house can reduce your energy requirements by as much as 124 kWh a month – saving roughly R50,00/month.

Installing a ceiling in six easy steps

  1. Check your roof-top for holes that will leak. Paint bitumen (from hardware stores) over these holes. Use plastic bags to block the holes between the top of the walls and the roof.
  2. Use nails to hang wire from one side of the room to the other  –  about 30 cm apart. The ceiling will then rest on top of these wires.
  3. Put two or three sheets of insulating cardboard between the wires and the roof. Remember to leave some space between the cardboard and the roof as this air gap produces the insulating effect.
  4. Use plastic tape to join pieces of plastic together (use black refuse bags or collect large pieces of plastic and open them out to make large sheets of plastic). Put these plastic sheets beneath the insulating cardboard and the wire. There must be no holes in the plastic.
  5. Hammer in a single layer of cardboard beneath the plastic. You can paint this cardboard if you like.
  6. You can then put up thin planks of wood to stop the ceiling from sagging.

Courtesy of Soul City/Development Action Group

Insulating your house

Insulation between your roof and ceiling really helps to keep your house warm in winter and cool in summer. It is generally cheap and very easy to do. The benefits of adding insulation lessen as the insulation gets thicker. Some insulation is therefore much better than no insulation at all. Plastering walls is also very cost-effective as it reduces the moisture capacity of the wall.

Use non-toxic, renewable or recyclable materials for insulation. Cardboard is effective but it does retain water and can burn easily. Soaking cardboard in boron and water makes it more fire-resistant and insect-proof. Boron is biodegradable and less toxic compared to other products on the market. Wait for the cardboard to dry out before using it. Place on a piece of plastic fat on the ground under heavy stones or bricks in order to fatten, before placing the treated cardboard on the inside of walls and ceilings.

Vermiculite is a light insulator that is safe to use, good for fire resistance and available from local hardware stores. Other insulating products from hardware stores or builder’s yards are gypsum board, hessian cloth and strong aluminium foil.

You can also tie plastic bottles very close together and place them between the top ceiling and the roof. These are insectproof and trap air, creating good insulation.

Read the guide

Green your heating and cooling

Considering ’embodied energy’

Each product used in the making of our house requires energy to make and transport it. This is called embodied energy. When building or renovating always consider reusing second-hand building materials. This saves energy, water, waste and money. The table below provides insight into the quantities of energy required to produce different materials.

Powering your home with renewable energy

The average house in South Africa receives more than 600 kWh of sunshine per day – much more than it will ever use. Photovoltaic cells (PVs) convert sunlight directly into electricity, which is stored in a battery system. PV panels are made from semi-conductor material, usually silicon that is chemically treated so that the upper and lower layers are oppositely charged. An electric current is generated from these opposing charges and flows through an external circuit. A battery pack stores the power until it is needed. A small household PV system can power two lights for four hours and a small black and white television or radio for two hours each day.

The initial cost of purchasing the PV panels and battery pack is still high however, and the system cannot easily or cost-effectively meet large electrical demands, such as cooking or heating. If you want to make your home a ‘green’ energy home, the most cost-effective choice would be to purchase ‘green’ electricity from a large, renewable-source electricity power producer when such options become available (such as through the Darling wind farm). Although you will continue to receive your electricity through the existing grid connection, you will pay a premium for this electricity (a rate higher than the usual electricity) and will receive a certificate to show that you have purchased it from a renewable source.

source: SMART Living Handbook

Get practical

Homemade air conditioner
Insulate your roof step-by-step
Making your home solar step-by-step

Other energy topics

A case study: Matthew Walton puts his house in order
Heating your water
Cooking
Lighting
Transport

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