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11_Annual%20Energy_2008

11_Annual%20Energy_2008 - Lecture 11 Calculation of Energy...

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Calculation of Energy and Costs for Annual Heating Lecture 11.
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News you can use: Discussion forum on the Arch. 140 WWW site – clearinghouse for HW and Final Project questions
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Let’s review: A figure called UA ref which was the rate of heat loss from a building expressed in the units of Btu/Hr F: UA ref = ( (UA)) + (F x P) + (VHC air x VOL x AC/hr) UA ref was one of the terms in our balance point temperature formula along with Qi (internal gains). UA ref .
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You will remember that balance point temperature, the outdoor temperature at which the furnace must come on, was defined as: T bp = T therm - ( Qi / UA ref) An assumed balance point temperature of 65 F is an important assumption in the conventional use of the degree day method for calculating annual energy consumption for heating a building. Balance Point Temperature .
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Professor G. Z. (Charlie) Brown advocates a balance point way of thinking.
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Is the Balance Point Temperature high or low? This is sort of a building science version of ‘am I hot or not?’ An aged, single- family, detached house in the country.
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Dover Centre “the Right Place to Grow Your Business” Is the Balance Point Temp. high or low?
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My old apartment in Back Bay Boston Is the Balance Point Temp. high or low?
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The Saskatchewan Superinsulated House Is the Balance Point Temp. high or low?
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A well populated gymnasium Is the Balance Point Temp. high or low?
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A graphic look at Balance Point Temperature Net energy loss if negative Net energy gain if positive Temperature scale used to locate thermostat setting, balance point temperature and rate of heat loss
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A graphic review of Balance Point Temperature Setting up a problem: Assume a 10,000 Btu/Hr rate of internal gains (Qi) and a thermostat setting of 72 F Thermostat setting Rate of internal gains (10,000 Btu/hr)
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T bp = T therm - ( Qi / UA ref ) Changing the rate of heat loss
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A graphic review of Balance Point Temperature The effect of different UA ref (heat loss rates). Higher rate of heat loss yields higher balance point temperature UA ref = 2000 Btu/Hr F
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A graphic review of Balance Point Temperature The effect of different UA ref (heat loss rates). Higher rate of heat loss yields higher balance point temperature UA ref = 1000 Btu/Hr F
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A graphic review of Balance Point Temperature The effect of different UA ref (heat loss rates). Higher rate of heat loss yields higher balance point temperature UA ref = 500 Btu/Hr F
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T bp = T therm - ( Qi / UA ref) Changing the rate of internal gains
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A graphic review of Balance Point Temperature With UA ref fixed at 1000 Btu/Hr F reduce internal gains from 10,000 Btu/hr to 5,000 Btu/hr Qi = 10,000 Btu/hr UA ref = 1000 Btu/Hr F
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A graphic review of Balance Point Temperature With UA ref fixed at 1000 Btu/Hr F reduce internal gains from 10,000 Btu/hr to 5,000 Btu/hr Qi = 5,000 Btu/hr UA ref = 1000 Btu/Hr F
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T bp = T therm - ( Qi / UA ref) Changing the thermostat
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