About 400 British companies have taken part in the 100 Days of Carbon Clean-Up challenge, for which they looked at ways to reduce their greenhouse gas emissions.
Fulcrum Consulting was one of the firms that took part in the challenge, organised by the Chartered Institute of Building Services Engineers (Cibse) and the Carbon Trust, and kept a journal of their progress on the BBC News website.
Fulcrum Consulting's building physics engineer, Susie Diamond, and Cibse chief executive, Stephen Matthews, answered some of your questions on how to save energy and reduce emissions from your buildings.
Q: Do you think there is any place for air conditioning in business or residential premises in the UK, except in special situations, such as operating theatres? Could all other cooling requirements be met through ventilation and shading?
Malcolm Scott, Wirral, UK
Stephen Matthews: You need to take each situation individually. Ideally, you will consider all forms of passive environmental control but in some situations natural cooling will be insufficient; for example, in densely occupied spaces like opera houses or concert halls.
Every attempt should be made to combine architectural form, materials and orientation to minimise the energy requirements which should be met by renewable resources wherever possible.
Naturally responsive buildings are healthy and sustainable, and much more can be done to achieve this than is currently the case.
Susie Diamond: My own experience of working in a naturally ventilated office in central London is this it is getting more uncomfortable during the summers. There were two weeks this year when it was so hot that it was difficult to work productively.
However, I believe that mechanical cooling is vastly overused in many homes and offices. The best strategy must be to reduce internal temperatures through passive means first, such as shading and ventilation, and limiting internal heat gains where possible.
I believe that there is a case for mechanical cooling in the future, particularly in city centre locations, but we need to think hard about minimising this cooling requirement and how to achieve what we need with minimal environmental impact. There are solutions out there.
Q: It appears that cavity wall insulation is a wise investment/contribution to carbon reduction. Unfortunately, my house is built of local stone on the outside and I am told that there is no way that I can insulate the cavity. Are you aware of any way I can insulate the cavity of an existing house built of external local stone with breeze block interior walls?
David Symes, Sheffield, South Yorkshire
Stephen Matthews: There will be a solution, but I would need more details to give David a full and correct answer. Perhaps the best bet is to contact the Energy Saving Trust for a local source of advice.
Susie Diamond: I am not an expert in cavity wall insulation, so I asked a colleague. He suggested that blown insulation of some kind may be a possibility but something that drains properly and does not get saturated. Try asking manufacturers, such as Warmcell, if they make a suitable product.
Q: Regarding fluorescent lamps, is it more efficient to leave them on all day rather than keep switching them on and off for quite short intervals? I was wondering if the current required to start the tube is greater than its steady state once it is lit?
Jon L, Hants, UK
Stephen Matthews: It is more energy efficient to switch them off.
Q: Switching off internal lighting is an obvious solution, but I would like to point out another related factor - businesses and municipalities that use floodlights just to satisfy the vanity of certain individuals who seem think this sort of thing "looks nice"? This is an obvious abuse and a blatant waste of energy.
Colin Henshaw, Dhaka, Bangladesh
Stephen Matthews: This is part of a much bigger debate on what constitutes waste and what energy should be regulated. One of the aims of the 100 days campaign was to get organisations thinking about all the different ways in which they could save energy and to plan for the future.
Q: I am interested in solar heating and the new wind turbines now on sale in the DIY supermarket B&Q. They state grants are available but where can I get the grants from, and does anyone else sell these items other than B&Q?
Steve, Derby, UK
Susie Diamond: The Department of Trade and Industry's low carbon buildings programme is probably your best bet for a grant. I am not aware of any other high street suppliers, but you could always buy direct from the manufacturers or try an online auction website, like eBay.
Q: I think the biggest problem is when it is not your building. What ways - apart from the obvious one of voting with feet - are there for a tenant business to put pressure on their landlord?
Candy Spillard, York, UK
Stephen Matthews: Negotiation can help. Also, as the issue of energy efficiency becomes more high profile, it will raise awareness among landlords in terms of the benefits for both them and their tenants and inform them of the choices they can make.
Susie Diamond: We are also tenants in our building, and the majority of the savings we made during our 100 days campaign were through tenant controllable means.
However, it might be worth discussing your concerns with your landlord, and suggesting ideas that they might implement. Cost is usually a major driver, but increased energy efficiency would cut utility bills.
If tenants are directly responsible for bills then they may agree to pay a slightly higher service charge in return for lower utility bills. My only advice is talk to them, they may surprise you.
Q: The idea of "bionic buildings" is interesting, especially when it comes to natural cooling via a subterrain process. Ancient Moghul emperors in India were reported to have used this. Do you have any background on this system and information on when and where in the world it was implemented?
Ravi Damodaran, Chennai, India
Susie Diamond: I believe the original idea came from termite mounds. It has been used successfully in various formats around the world.
The basic idea being that by bringing ventilation air into a building via underground tunnels, the stable underground temperatures will cool this intake air in summer and warm it in winter.
The amount of cooling/heating benefit received depends on a number or factors including the length and shape of the intake tunnels, the annual ambient temperature range and the volume of intake air.
We have used this technique on a number of projects, including some in India and Egypt as well as the UK.
Q: I am afraid that Fulcrum have cheated with their carbon-saving figures. Their biggest claimed carbon saving is by switching to using recycled paper.
Unfortunately, they did not save any energy by doing this switch. The paper manufacturer made the saving (assuming that is, that they made recycled paper instead of virgin paper).
Only the organisation using the raw energy can claim the saving, otherwise you would get double, triple, quadruple, etc, savings. The rule for energy saving must be reductions at the user's gas, electric and water meters, not somebody else's.
John Pennifold, London
Susie Diamond: We stand by our decision to include this carbon saving in our total. If we did not make this change to our purchasing policy then there would be less demand for the recycled paper products.
Manufacturers only produce recycled copier paper because there is demand for it; we are therefore the driver as purchasers. Quantifying our carbon savings as a result of the initiatives we implemented during our 100 days was largely for fun and to illustrate our progress.
As I mentioned in the journal, many initiatives were difficult or impossible to quantify in terms of carbon savings, but this does not mean they do not have environmental benefits.