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Some simple paybacks for different energy related retrofitting measures

  • 04-10-2007 7:39pm
    #1
    ircoha
    Closed Accounts Posts: 2,290 ✭✭✭


    The attached may be of interest: I post it just for info and not to start a debate of any kind.


Comments

  • #2
    Mellor
    Registered Users, Registered Users 2 Posts: 39,902 ✭✭✭✭Mellor


    Its worth pointing out that these figures apply to retrofit, new build would be alot better. This is because the calculation is worked out by the savings per year and divided this by the total cost of the product. There is a huge error here as some products are essential and the figure should be savings per year divided by additional cost. This applies to boilers and other items that people will always have. For example, there is zero payback time on CFLs. As some bulbs coast more, but some are the same price, also some last longer and some last the same. These cancel each other out and energy savings are direct savings.


  • #3
    Mellor
    Registered Users, Registered Users 2 Posts: 39,902 ✭✭✭✭Mellor


    Oh, and forgot to mention that energy rises will continue to rise (and not just fossilfuels based ones) and therefore the projected payback time will be much less


  • #4
    10-10-20
    Registered Users, Registered Users 2 Posts: 8,073 ✭✭✭10-10-20


    Solar doesn't come out well from this study - but again performance of these devices is improving from day-to-day. I think I calculated 35 years payback on a 350w solar system with battery backup and inverter etc recently.
    I know a guy down in Wicklow who managed to modify a APC 2kW UPS to give him inverter capabilities... all recovered from a skip!


  • #5
    ircoha
    Closed Accounts Posts: 2,290 ✭✭✭ircoha


    Thanks for inputs: I suppose PV is not really a real retro product.

    On the cost of enegy going up, unless the rate of increase is substantially greater than inflation, then future price increases will not 'hurt' so much in a present value calc. If we have a massive spike then yes the furure savings will be greater.

    The other point worth noting is giving PV some credit for the reduced CO2 emissions.
    This has to be offset against the CO2 emissions due to their production.

    10:10:20.

    Can you please share the outline of your calc with the forum: it would add value to the discussion.


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