Dienstag, 15. November 2011

The environmental impact of optimum insulation thickness for external walls of buildings

Information on article



This article was written by O. Altan Dombaycı of the Denizli Vocational College, Pamukkale University, Denizli, Turkey, received 29 June 2006 and accepted 31 October 2006.
In this study environmental impact of optimum insulation thickness in external walls has been investigated for the case of Denizli, Turkey. In the calculations, coal was used as the fuel source and the expanded polystyrene as the insulation material. The results proved that when the optimum insulation thickness was used, energy consumption was decreased by 46.6% and the emissions of CO2 and SO2 were reduced by 41.53%.

Points included in the paper

The key points in this paper are as follows:

·         There are approximately five months of the year in Denizli where there are heating requirements, during this period buildings generally use low quality coal and less oil, because of the costs, which causes high air pollution in the city, especially buildings with inadequate insulation that burn more fuel.
·         Environmental problems are due to a combination of several things such as, population increase, increase in energy consumption and the rise in industrial activity (including in the city of Denizli in Turkey, which is the main focus of this article).
·         Global warming or the greenhouse gases effects are the biggest environmental problems that face us as a race at the moment.
·         The rate of energy consumption related to heating is important when looking at air pollution and is around 30% in Denizli.
The externals walls, in Denizli generally, have a structure called a sandwich wall consisting of 2 cm inner plaster, two pieces of 8.5 cm horizontal hollow brick and 3 cm external plaster.

This article states that the external walls release quiet a large amount of heat but, if they were to be filled with insulation, expanded polystyrene being the recommended one, then the rate of fuel consumption i.e. coal burning, will decrease therefore reducing the amount of green house gases, CO2 and SO2  being emitted.
In a previous work it was found that the insulation thickness currently being used in buildings in Denizli is 0.0225 m. From the figures in the article the use of 0.095 m insulation thickness instead of 0.225 m, would reduce the amount of fuel and emissions by 63%. Therefore it seems, the thicker the insulation the better the results.
The unfortunate thing is that not all the heat is lost through external walls, 65.2% of total heat loss occurs through external walls, ceilings and floors and a further 34.8% is lost through windows. The application of optimum insulation thickness to these sections of the building would contribute to energy savings of up to 65.2% and the amount of fuel consumed and emissions to the environment reduced by up to 41.53%.
Conclusion
The article clearly states that the use of insulation would reap great rewards in relation to the environment and for long term energy savings. However I do have a few issues with some of the points in the article which are;
·         The type of insulation being used.
·         The optimum insulation thickness depends mainly on the cost of insulation material, cost of energy, yearly heating and cooling transmission loads, efficiency of the heating system, coefficient of performance of the cooling equipment, building lifetime, and inflation and interest rates, can everyone afford to insulate their house to the standard required to achieve the requirements and the maintenance that is involved?
·         Oil consumption was never looked at, even though it is not used in such quantities as coal.
·         If refrigerative air-conditioning is employed in a hot, humid climate, then it is particularly important to seal the building envelope. Dehumidification of humid air infiltration can waste significant energy.

H





Kommentare:

  1. Dear Kieran,

    well structured your evaluation. You were pointing out that you had an issue with the type of insulation being used. Do you know the insulation type?

    Further you explain the set up of components for standard walls in Denizli, without mentioning insulation, later you write:"the insulation thickness currently being used in buildings in Denizli is 0.0225 m". Is that from back in the days or still current standard for new build?

    As you have pointed out, optimum insulation levels depend on pricing of materials and fuel. On the background of climate change you also mention CO2 and SO2 emissions. I wonder if optimum insulation levels could be determined by only looking at a initial cost and running cost comparison. As an initial investment cost will quickly be offset by running cost. A sensible calculation would probably use a payback period of 10 Years. What do you think?

    By the way, I just learned that good thermal performance (optimum insulation levels)requires an airtight building. The cost for airtighness should therefore be included in the cost for insulation. (According to SIGA.CH average cost for airtightness materials is €450/100m2)Just for anyone interested. Keep up the good work.

    Passive Attack

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  2. Henrick Thank you for your comment.
    The insulation type mentioned may be the best type but I have just one or two issues with the type of insulation,

    The cost can be high compared to traditional insulation. Which as you know is very important in the current economic climate.

    Also being from a health and safety backround, Polyurethane insulation contain hazardous chemicals such as benzene and toluene. These can pose potential health hazards and are of environmental concern during raw material production, transport, manufacture, and installation.

    If you do not wear a protective mask or goggles, it is possible to temporarily impair your vision using this type of insulation by(2–5 days)

    From the article in Denizli 0.0225 m is the insulation thickness being used at the moment, this it is said if up graded to the use of 0.095 m insulation thickness, would reduce the amount of fuel and emissions by 63%.
    I understand your view on the costs point of view but as i commented on anthonys blog, try selling that idea to a young family who have lost their jobs, It is not just a case of, "Gimme the money now and you will see the results in 5 or 10 years" People may not have the initial lump sum to hand over straight away. I thought it was just worth mentioning.

    Thanks again,

    Kind regards,

    Kieran

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  3. Hi Kieran, thanks for your feedback. I am shocked to hear that polyurethane insulation can interfere one's vision. I never heard that before, even though I knew that it was made from chemicals. Thanks for letting me know.

    I totally understand your comment on the extra costs, but here probably legislation has to come into play to ensure a decent standard in energy and environmental related terms. People always have to make compromises. Thanks anyway.

    passive attack

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  4. Hi kieran

    I am also very suprised that polyurethane insulation can interfere one's vision. that is very intresting to know from a health and safety background myself. you also mention that it can have a high cost, i fully agree that in our current situation it can be hard to give extra money for a product that poses the same principal as tradional insulation which will pose a big decision for couples. very good article.

    good work.

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