One of the most effective ways to save energy at home is to insulate your ceiling. Now, the best time to insulate a home is during construction (note, in compliance with new SANS regulations in South Africa, as of January 2013, all new homes built must have ceiling insulation), but for the majority of home owners that’s just not an option. Fortunately, ceiling insulation is easy to install. You can even do it yourself if you have the proper safety equipment and some (physical) energy to spare.
Here’s a brief overview of ceiling insulation to help you make an informed decision when the time comes to insulate your house.
Types of insulation material
Many different types of material are used for insulation. They tend to be suited to different purposes, different buildings and different climates. According to Eskom’s handy PDF on insulation in South Africa, the range of insulation materials includes:
- Synthetic polymers, like polyester, polystyrene, polyicynene, polyurethane and polyisocyanurate.
- Mineral wools, like fibreglass, rock wool, slag wool and stone wool.
- Minerals, like vermiculite and perlite.
- Natural plant materials, like cellulose, cork, hemp, cotton, straw, sawdust and hemlock fibre.
- Animal fibres, like wool.
- Shredded recycled paper, like cellulose loose-fill.
Not all materials are created equal, which is why you need to look out for the R-value. The R-value is the thermal resistance and it tells you how well a particular material limits heat transfer. The higher the R-value, the more effectively it insulates.
Choosing R-values by climate
That’s not to say that you should choose the highest R-value you can find and go for it. Different R-values work best in different climatic conditions, so what works well in Joburg might not work well in Cape Town.
South Africa is divided into six climatic zones. Eskom gives each zone a minimum R-value for roof insulation. You also have to consider the dominant direction of heat flow, which also varies by climate. Downward heat flow occurs in climates with hot summers (when hot air moves into buildings), while upward heat flow occurs in climates with cold winters (when heat is lost). Some places have equal insulation requirements no matter what the season (combination of upward and downward heat flow). According to Eskom, humid climates tend to require high R-values for downward heat flow and low R-values of upward heat flow.
Let’s put all of that in bullet-points:
- Zone 1: Cold interior, which stretches from Sutherland though Middleburg, Bloemfontein and Kroonstad and up to Joburg and Midrand. Minimum R-value – 3.7. Upward heat flow.
- Zone 2: Temperate interior, which includes Worcester, Craddock, Pretoria, Mmabatho and Polokwane. Minimum R-value – 3.2. Upward heat flow.
- Zone 3: Hot interior, which includes Nelspruit, Phalaborwa and Makhado. Minimum R-value – 2.7. Downward and upward heat flow.
- Zone 4: Temperate coastal, which runs from Alexander Bay to Cape Town and on past Port Elizabeth. Minimum R-value – 3.7. Upward heat flow.
- Zone 5: Sub-tropical coastal, which runs from East London through Durban and past St Lucia. Minimum R-value – 2.7. Downward heat flow.
- Zone 6: Arid interior, which includes Kimberley and Upington. Minimum R-value – 3.5. Upward heat flow.
Types of insulation
According to a great home insulation guide, there are three types of insulation:
1) Bulk, which is made up of fibres that trap air pockets that conveniently limit heat flow. Bulk insulation materials include fibreglass, rock wool, natural wool, polyester, polystyrene, cellulose fibre (loose fill)
2) Reflective, which limits infrared radiant heat transfer. Materials include foil sheets laminated onto paper, concertina-style foil and multi-cell foil products.
3) Composite, this is some combination of bulk and reflective insulation.
Most of the types are available in batts or blankets, which are easy enough to install yourself, provided you have the right safety equipment, including a dust mask, goggles, gloves, old long-sleeved shirt and closed shoes.
The most commonly used insulation in residential South Africa is bulk insulation and the most common materials include:
- Fibreglass (glass wool) (Think Pink – Aerolite)
- Polyester fibre, which is often made from recycled PET bottles, so it’s a great option for people who really want to get into a green mindset.
- Cellulose loose-fill, which is another great eco-friendly option as it’s made from shredded recycled paper. The downside is that it settles over time and this decreases the R-value.
- Rigid board vermiculite
- Expanded polystyrene (EPS), which is recyclable, so it’s another winner for eco-warriors.
Up to 51% of your home’s heat can be lost if your ceiling isn’t properly insulated. Think about what that means for heat coming into your home during the height of summer. If you want to cut down your energy bills, ceiling insulation is the way to go. According to estimates, ceiling insulation pays for itself within 2 – 3 years, but the effects on your monthly electricity account are immediately obvious.
Image Credit: mjtmail (tiggy), CC BY 2.0, Via Flickr