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  1. #1
    Join Date
    Sep 2006
    Posts
    136

    How can I measure energy savings of new furnace?

    This seems like such an easy question, but I believe it is hard to come up with an accurate way to measure.

    The easiest is to look at a time frame (winter) before putting in the furnace and then measure the energy usage for the next year and see what the difference is in usage.

    But here is a problems with that method. The weather could be significantly different and the savings could be based on the weather change and not the windows. Another issue for me is that I want to make other energy efficient changes in my house, but if I do that now, I won't know which change caused the savings.

    So my next thought was to measure a shorter period of time. Say overnight or on a daily basis. Again, if the temps are different it is not a valid measurement.

    So, does anyone have a way of measuring before and after energy usage that takes temperatures into account to provide an accurate energy savings number?
    Thanks,

    Mark

  2. #2
    Join Date
    Feb 2010
    Location
    In a boiler room
    Posts
    7,046
    "Since gas prices vary some from month to month, and winters differ in severity, you might want to compare present vs. previous weather conditions. Then you can base your comparison on the number of therms used, rather than the $ amount of gas bills.

    Go to wonderground.com, enter your zip-code at the top. Hit enter. Then, wheel down (or edit/find) to 'detailed history and climate'. Click 'view'. The 'Daily' tab is highlighted, but click on 'custom'.

    Enter the 'from' and 'to' dates of your gas bills and click 'go'. Under the 'Sum' column, look at the total of Heating Degree Days (HDD). The larger the number, the lower the average temperatures (colder weather).

    If you divide the number of therms used, by the total of HDD, you then will have a figure by which to compare your heating efficiency present vs. past. So, even if your billing periods are different, you still comparing how much gas you used vs. how cold it is (was).

    In the event you cook and heat with gas, you can deduct your average gas usage of the months with no HDDs.

    Amp"


    The above may help, it is from a post by ampulman in another thread named Lennox G61MPV.

  3. #3
    Join Date
    Sep 2006
    Posts
    136
    Thank you. That was very helpful.

    BTW, it's wunderground.com, not wonderground.com!
    Thanks,

    Mark

  4. #4
    Hi Mark...you have a good question and one that is not black and white. In general the manufactures provide very useful data about the efficiency of your furnace along with projected annual savings. If you can not find this on the Internet I suggest you contact the respective dealer for this information. This information is not readily available sometimes because most customers are not that knowledgeable about system specifications et cetera, therefore the information is not easy to obtain. I hope this helps you out...good luck. Regards.

  5. #5
    Join Date
    Mar 2010
    Location
    Brampton, ON, Canada
    Posts
    22
    Hi Mark,
    I hope it is not a York. I having nightmare & sleepless night because of my unit. First of anyone reading this I can truly say that having a right sized BTU unit for size of your house is most important. I had the pleasure of York Canada messing up a warranty replacement of the current model YP9C60 to a YP9C80 which I just look at consumption for month of March, Feb, and part of Jan; a sizeable difference of 20K BTU on a 1300 square feet house this past winter is 55% less efficient than its smaller model for this house. Though both 60 & 80 BTU is better than my mid efficiency by at least 60% savings.

    I agree it is hard to calculate, but those three factors do make sense, outside weather, your house heat loss ( manual J calculation ?) prices of gas will always change.
    Last edited by anh2; 03-19-2010 at 04:16 PM. Reason: grammar

  6. #6
    Join Date
    Jul 2008
    Location
    Rochester NY
    Posts
    4,699
    Track usage, not price, and do it year to year to average out inconsistancies. Like your car, tracking one tank is fairly pointless.

    Make sure hdd are fairly constant but don't get to hung up on it.
    Which makes more sense to you?
    CONSERVATION - turning your thermostat back and being uncomfortable. Maybe saving 5-10%
    ENERGY EFFICIENCY - leaving your thermostat where everyone is comfortable. Saving 30-70%

    DO THE NUMBERS! Step on a HOMESCALE.
    What is comfort? Well, it AIN'T just TEMPERATURE!

    Energy Obese? An audit is the next step - go to BPI.org, or RESNET, and find an auditor near you.

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