Category Archives: Eric Mair's Energy 101

A collection of articles by Eric Mair, energy and sustainability consultant, and advisor to our organization.

Eric Mair’s Energy 101: Part 9

Dear friends,

Last month we talked about designing and planning a new building. This month I’d like to look at the materials you will be using to build it. This is where an energy consultant will be a very useful addition to your team.

In this section you need to understand the concept of “Embedded Energy” – how much energy was used in manufacturing/processing of the product and delivering it to your site? Some products have a high embedded energy because of the materials they are made from or the process through which they are produced. Cement is one of those. Others come from far away and their embedded energy component is largely due to the transport miles accumulated on the journey to your site. High embedded energy = high carbon/environmental footprint.

Before purchasing new materials consider what is available from recycled or reclaimed materials. This does not necessarily mean products will be inferior. Products like Cape Brick, which utilise recycled building rubble to produce a fine quality building material, are an essential part of a sustainable building. Reclaimed building materials can be economical and very attractive plus they have a lower carbon footprint.

Try to use local products – ‘local is lekker’ as the saying goes, but make sure the durability aspect is covered too. On the other hand “expensive” and “imported” are not necessarily guarantees of quality either! Here the important consideration is the expected useful lifetime of the product in its current form and how much maintenance it will require in its current application. In other words how long will it last and how much work will it take to keep it working/looking good? This is important too because if you buy a “natural product” that is difficult or impossible to clean for example, you won’t be able to live with it for long and it will need to be replaced. This is not sustainable, you can’t continue replacing stuff every couple of years – there just isn’t enough “stuff” to maintain the flow of products if everything needed replacement every couple of years. Try to buy the best quality you can afford with a view to making it last and be maintenance free for as long as possible.

One should also consider what will happen to the “stuff” we buy at the end of its life – how easy will it be to re-assimilate the material into the natural cycle or to recycle it into something else useful?

Some materials are easy to re-assimilate back into nature. Things like wood and wool, paper and cotton. But these are often difficult and/or expensive to maintain, so the decision becomes a balancing act of embedded energy versus energy in use. The longer the material lasts usually means it is most energy efficient. E.g. aluminium has an enormous embedded energy component but it is usually made locally (in South Africa – you should check this, it’s important), it costs next to nothing to maintain and lasts for ages. In addition to that it is wholly recyclable into more aluminium products. I’d suggest that in some cases, despite its huge embedded energy component, aluminium could be considered a sustainable building material provided it is correctly recycled at the end of its life.

Wood, provided it comes from a sustainable source (check for the Sustainable Forestry Initiative (SFI) or Forestry Stewardship Council (FSC) stamps), is widely regarded as a sustainable building material. It needs periodic maintenance but as long as this is carried out in an environmentally sound manner i.e. not with things like creosote, the product will last for a very long time and, of course, it’s easily re-assimilated back into the natural cycle at the end of its useful life.

There is a plethora of environmentally friendly or sustainable building products on the market today and more being announced all the time. Your energy consultant will help you work out which is right for your particular application.

Next month we’ll have a look at heating and cooking. Download this article here.

©Eric Mair, July 2009


Demystifying Renewable Energy: an Eric Mair presentation

Dear friends,

Eric Mair, from Capstone Renewables, will be hosting a Demystifying Renewable Energy presentation on the 8th of August 2009. This is a 90 minute presentation on what can be and, indeed, is being achieved both in the domestic and utility scale markets with renewable energy resources and technology available today.

It is an exciting power point-driven journey from the ubiquitous solar water heater through to the cutting edge of concentrated solar thermal generators.

The presentation also delves into:

  • Wind power, looking at both horizontal and vertical axis wind turbines and the advantages of each.
  • Ground sourced heat and how it works.
  • An overview of hydro-generation, wave and tidal
  • And a section on bio-fuels.

This is not a highly technical presentation and is aimed at:

  • Anyone who wants to know more about renewable energy but didn’t know who to ask.
  • Those who feel overloaded by jargon and techno-speak and need an explanation in layman’s terms.
  • Anyone who is interested in getting in touch with the latest developments and what is happening globally in the field.

Questions are encouraged during the presentation and there will be an opportunity for discussion afterward as well.

VENUE: Gatehouse, 91 Brommersvlei Rd, Constantia
DATE: August 8th 2009
TIME: 15:00
COST: R50 per person

Space is limited at this venue so please let Eric know if you are coming. Contact Eric on 082 496 0113, or



Energy 101: Planning and design of buildings

Bearing in mind the energy efficiency mantra:  The cheapest energy is the energy you don’t use (where “cheapest” refers to both finance and environment). The most efficient way to keep your spaces warm in winter and cool in summer is to design and build them with energy efficiency in mind in the first place.  Insist that your architect consults with an energy consultant to help him/her achieve the best possible energy efficiency in the design phase as well as in the materials and equipment specifications.

Passive Solar is the technique used to design and build energy efficient buildings.  There is a lot of information on the web (just Google “Passive Solar Design”) and libraries of books have been written on the subject.  It’s not a new concept either, I remember as a child, my parents talking about the benefits of the south facing aspect of a house or garden (I grew up in the UK).  In South Africa we are south of the equator so we want our houses and offices to be facing north to make the best use of the winter sun and to help shade us from the worst of the summer heat.

The basic principle of passive solar design is to enable as much heat from the winter sun as possible to enter the space and warm the floors and walls so that they can re-radiate that stored heat after the sun has gone down.  At the same time, the building needs to be able to protect itself from the heat of the summer sun.  Roof overhangs, awnings, balconies, strategically planted deciduous trees and cross ventilation are just some of the techniques available to control summer temperatures and year-round airflow through the building. Another aspect of passive solar design is to maximise the amount of natural light entering the building thereby minimising the amount of artificial lighting needed during the day.

If your building is properly designed it will be well insulated, preferably with an environmentally friendly system such as Eco-Insulation in the walls and ceilings.  Floors are a bit more tricky to insulate because the insulation has to be integrated into the slab to be of any real use and this means you have to go with one of the less environmentally friendly options.  Ask your energy consultant for advice on this.

The very best and most efficient way of heating and cooling any space, however large or small, is to design in a ground sourced heat system.  It is by far the most energy efficient means of artificially controlling temperature inside a building; it has a life expectancy 3 or 4 times greater than the equivalent air-sourced systems AND you get free domestic hot water as a by-product!

In our climate it is possible to design and build a building which requires no electro-mechanical heating, ventilation or air conditioning (HVAC) at all, and this is what we should be striving for in the design and planning stage of any building or group of buildings. Download a copy of Energy 101: part 8.

Next month we will be looking at what materials to use in your new building, bearing in mind issues such as:

  • Embedded energy – how much energy was used in making the product and delivering it to your site.
  • The expected useful lifetime of the product in its current form and how much maintenance it will require in its current application.
  • What will happen to it at the end of its life – how easy will it be to re-assimilate the material into the natural cycle or to recycle it into something else useful?

*This is part 8 in Eric’s Energy 101 series

Eric Mair