# Thread: cooling degree days for commercial building

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## cooling degree days for commercial building

hello

i am trying to estimate the energy savings in the interior mall , (arcade & attrum) of a shopping center from seting up the cooling setpoint thermpurture of rooftop packaged units , the zone im studing is surrounded by (conditioned)retail stores witch im not including in the study,the roofs & ground are not insulated, the internal loads & solar gains are very importante.

So my question is can i use the variable base degree day methode to estimate the savings by reducing the cooling load when seting up cooling set point?

I performed a regression analyses i found good correlation between HDD & the electrical consumption , but no correlation between the CDD & the Electrical consumption .

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How to Calculate Cooling Degree Day (CDD)
There are several ways to calculate CDD. The more detailed a record of temperature data, the more accurately the CDD can be calculated.

1. Subtract 65 from the average of a day's high and low temperatures. For example, if the day's average temperature is 75o F, its CDD is 10. If that day's average is below 65, the result is set to zero. If every day in a 30-day month had an average temperature of 75o F, the month's HDD value would be 300 (10 x 30). The nominal settlement value for that month's weather derivative contract would, therefore, be \$6,000 (300 x \$20).

2. Subtract 65 from each half-hourly temperature reading, with the provision that negative values be set to zero, sum the result and divide by 48 (48 half-hours in a day). Then sum that value over 30 (for a 30-day month) and multiply by \$20. If a given day's value is less than or equal to zero, that day has zero CDD. But if the value is positive, that number represents the CDD on that day.

For all methods, if the value for any given day is less than or equal to zero, that day has zero CDD. But if the value is positive, that number represents the CDD number of that day.

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Are you a professional yourself or taking someone else help?

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Yes, you can use degree days method.

If you don't have good correlation between the CDD & the Electrical consumption, try and find another variable to add into the regression analysis.

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Another way to go is to use a Chiller assessment tool. Contact your local JCI rep. and request them to send the Yorkworks CE software (requires registration). Yorkworks CE is a suite of software. The one to use is YorkCalc. Within YorkCalc you would select 'Unitary' then 'Rooftop'. Plug in all the data and run a model. Change to a new setpoint and run the model. Lets you know all the energy consumption + more.
Bit a of a learning curve (like with all s/w). See attached.

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