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Green Building Bible, Fourth Edition
Green Building Bible, fourth edition (both books)
These two books are the perfect starting place to help you get to grips with one of the most vitally important aspects of our society - our homes and living environment.

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    • CommentAuthordicktc
    • CommentTimeSep 14th 2016
     
    I am looking at SAP calculations for a new build - the full printout which runs to about 30 pages. Section 10a ("Fuel costs") takes the various energy requirements such as Space Heating and Lighting, and multiplies the "Fuel kWh/year" by "Fuel price p/kWh" to arrive at a "Fuel cost £/year". So far so good. It then does a similar calculation for the energy generated by solar PV which it then nets off against the fuel costs.
    I am assuming this PV figure is based on the total predicted PV generation for the year. However why would it be multiplied by the standard price for a unit of electricity? Isn't this misleading?
    If my PV system generates electricity when I'm out all day and there is no demand, then surely that electricity will be sold back to the grid at a considerably worse unit price than the price I have to pay to buy electricity, so in reality it won't offset my energy costs in the way the SAP report suggests.
    Grateful for your comments if anyone knows about this.
    Thanks
    • CommentAuthorbarney
    • CommentTimeSep 14th 2016
     
    I'm not a SAP assessor, but I understood it to be based on a notional 50/50 split between use and export and should have the import and export cost included at the relevant values.

    I'm not sure the assumption should be sale cost equals import cost

    Regards

    Barney
    • CommentAuthordicktc
    • CommentTimeSep 20th 2016
     
    Thanks Barney. I am going to ask my SAP assessor to clarify this point with the company that provide him with the SAP Calc software.
    Cheers
    Dick
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