[Greenbuilding] Night Time Insulation+Spreadsheet Model

[Eli Talking]

Pardon my error.The area of glazing covered by night insulation was 120sf. 
Not 50sf as stated in last paragraph of my previous message.
Eli
----- Original Message ----- 
From: "Eli Talking" <elitalking at hughes.net>
To: <greenbuilding at listserv.repp.org>
Sent: Saturday, January 05, 2008 11:24 AM
Subject: [Greenbuilding] Night Time Insulation+Spreadsheet Model


>I was glad to see this list returning to my Greenbuilding folder.
>
> I had begun a discussion prior to list maintenance break about the energy
> savings of night time insulation.  To better understand this issue, I
> developed a spreadsheet using separate lines for each of 24 hours and
> entered the predicted hourly temperature from the weather channel web site
> for my town.  This is a prediction and not a record.  However, I think it 
> is
> in the ballpark.  I also enetered the sunrise and sunset so I can separate
> night from day.  From this information I can determine how may degree 
> hours
> are it the daylight and in the darkness.  Therefore, I was able to assess
> heat load for a given area with a given R value.  Using the nightime 
> degree
> hours I could see what the savings in energy was in btu's for covering
> windows at night.  What I discovered was the night time heat loads 
> generally
> was between 61%-65% of the degree hours in the day.  This was the range on
> both  colder and warmer 24 hour calander days.  However, on one day, which
> was an exception, I got 55%.  Now, I have some bases for a rule of thumb
> being that 62%+- of degree day is for heating the night.  However, this
> likely will change as the days get longer.  So, I am going to continue 
> this
> excersize.
>
> I found a source of regional data from a regional airport that has hourly
> temperture as well as other weather data such as relative humidity that
> dates back to 1965.  From this I could determine an average hourly
> temperature for each hour of the year.  However, I could also get barried 
> in
> numbers. To do this I need to learn more about importing data to
> spreadsheets.  I may also need to upgrade to Excel over the MS Works 
> program
> I now use.  I am undecided about going that far.  However, I believe this
> has been a good excersize to get a better feel for temperature profile 
> over
> the 24 hour period.
>
> By the way, the savings was not that great.  However, I am pasting in the
> results from yesterday that was quite cold for 50sf of R6 night time 
> window
> insulation over R2 window with current energy prices for propane and fuel
> oil.
>
> Eli Fishpaw
> Architect in Lexington, VA
>
> Avg24 25
> DD24 40
> DH24 960
> 0
> Day Hours 10
> Night Hours 14
> DH day 377
> DH night 583
> Night part of total 0.61
> Area 120 sf
> Window R 2 hr sf F/btu
> Night 34,974 btu/night
> 91,600 btu/gal propane
> 0.3818 gal propane
>
> Night 34,974 btu/night
> 140,000 btu/gal #2 fuel oil
> 0.250 gal #2 fuel oil
>
> Cover R 6
> Total R 8
> 8,743 btu/night
> 91,600 btu/gal propane
> 0.0955 Gallons Propane Saved by Solar
> nightly savings w/cover 0.286355076 gallons Propane
> Propane Price $2.55 /gal
> Savings/night $0.73
>
> 34,974 btu/night
> 140,000 btu/gal fuel oil
> nightly savings w/cover 0.2498 gallons Propane
> Propane Price $3.15 /gal
> Savings/night $0.79
>
>
>
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