Air Cooling Energy La. based Savings from Reduced Lighting Heat Load

[energy_rater_La]

Air Cooling Energy Savings from Reduced Lighting Heat Load

Fraction of the year of the cooling season. 39.6weeks(Data for New
Orleans from source reference)
Fraction of daily load met by mechanical cooling. (How much of the
lighting system's heat must be removed by the cooling system?)0.90For
incandescents, usually this is about 90%, with 10% dissipated.
Air cooling system's COP. For every watt (W or kW) put into a system, 2.7
watts (W or kW) of cool air is produced.2.70The actual figure can vary,
however, due to a range of factors; the 2.7 figure can be used although
it is best to use the actual system's coefficient of performance.

Fraction of Lighting Savings as Air Cooling Savings =$/kWh Elec Rate
Fraction of the year of the cooling season0.76Yr Fraction (weeks/52)
x Lighting Load Met by Mechanical Cooling =0.69Yr Fraction x Fraction of
Daily Load Met by Mech. Cooling
÷ System's Coefficient of Performance=0.25kWh per kWh Elec. Lighting Load
Saved$0.100

Sample Typical CFL Types and WattagesQty. to ReplacexCFL Watts (each)CFL
Watts InstalledIncand. Watts (each)Incand. Watts ReplacedTotal Watts
SavedEst. Hours On/ DayEst. kWh Saved per Year
5-watt (25-w equivalent) 0x50250040
11-watt (50-w equivalent) 0x110500040
11-watt vanity (40-watt equivalent) 6x1166402401742122
15-watt (60-w equivalent)2x153060120905158
14-watt (60-w equivalent) 6x1484603602765484
13-watt (60-w equivalent)2x132660120945165
18-watt (75-w equivalent) 6x18108754503425600
23-watt (100-w equivalent) 2x23461002001544216
26-watt (100-w equivalent) 2x26521002001484208
23-watt indoor/outdoor (120-w equivalent) 2x23461202401944272
40-watt (200-watt) ECObulb0x4002000040
65-watt (120-w equivalent)0x6501200040
65-watt (300-watt equiv.) 0x6503000040
3-watt CHANDALIER (25-w equivalent) 0x30250040
18-watt CHANDALIER (40-w equivalent) 0x180400040
7-watt CANDELABRA (40-w equivalent) 6x742402401984278
9-watt CANDELABRA (40-w equivalent)6x954402401864261
12-watt CANDALABRA (50-w equivalent)0x120500040
11-watt FLOOD (50-watt equivalent)0x110500010
14-watt FLOOD (65-watt equivalent)0x140650010
14-watt FLOOD (50-watt equivalent) 0x140500010
19-watt FLOOD (85-watt equivalent)8x19152856805281185
3-WAY 14/19/32-w (40-, 75-, 150- eq.)0x21.70.088.30.00.040
3-WAY 10/20/28-w (50-, 75-, 150- eq.)0x19.30.091.70.00.040
3-WAY 12/20/24-w (30/70/100 eq.)2x18.737.366.7133.396.04135
Total Watts:74332232480kWh/yr:20,000
Direct Electrical Savings (Incandescent - CFL)kW:2.48$/yr:$2,000
Fraction of Lighting Savings as Air Cooling Savings0.25(from earlier
calculation above table)$/yr:$508
Total Annual Savings:$2,508

Source: Robert Rundquist, PE is the president of R.A. Rundquist
Associates of Northampton, MA and a professional engineer with nearly
three decades' experience in heating, ventilation and air conditioning
(HVAC) system design, energy analysis and energy calculation research. He
offers a formula to assess a more accurate figure for air cooling energy
savings that was derived from both independent research and research
conducted for the American Society of Heating, Refrigeration and Air
Conditioning Engineers (ASHRAE). It has been validated by DOE-2 computer
runs and other methods.

__________________________________________________ _______________________
________________________________________
How to Calculate Air Cooling Energy Savings
Robert Rundquist, PE is the president of R.A. Rundquist Associates of
Northampton, MA and a professional engineer with nearly three decades'
experience in heating, ventilation and air conditioning (HVAC) system
design, energy analysis and energy calculation research. He offers a
formula to assess a more accurate figure for air cooling energy savings
that was derived from both independent research and research conducted
for the American Society of Heating, Refrigeration and Air Conditioning
Engineers (ASHRAE). It has been validated by DOE-2 computer runs and
other methods.
1. Lighting energy consumption must be reduced by a specific amount that
stays constant throughout the year. This is most predictable in a
retrofit, but can also work for some controls and other applications
where hours of operation are reduced.
2. Determine the fraction of the year of the cooling season. (Download
The Advanced Lighting Guidelines to get typical cooling seasons in the
US)
3. Determine the fraction of the daily load met by mechanical cooling.
Basically, this question asks, how much of the lighting system's heat
must be removed by the cooling system? Usually this is about 90%, with
10% dissipated.
4. Determine the air cooling system's coefficient of performance. Tests
on cooling systems have shown that for every watt (W or kW) put into the
system, 2.7 watts (W or kW) of cool air is produced. The actual figure
can vary, however, due to a range of factors; the 2.7 figure can be used
although it is best to use the actual system's coefficient of
performance.
5. Calculate using the formula below:
Fraction of Lighting Savings as Air Cooling Savings =
Fraction of the Year of the Cooling Season
x Lighting Load Met by Mechanical Cooling
÷ System's Coefficient of Performance
6. Example: Suppose we retrofit a system in Raleigh, North Carolina,
which has a cooling season of 30 weeks, and remove 20,000kWh from the
lighting load.
Fraction of Lighting Savings as Air Cooling Savings =
30 ÷ 52 = 0.5769 or 0.58
x 0.9
÷ 2.7
= 0.19
That means that for every 1 kWh of lighting saved, we save 0.19 kWh of
air cooling energy. In our example, this means that we have removed
3,800kWh (20,000kWh x 0.19) of air cooling load. If the local utility
charges an average commercial rate of $0.065 per kWh, then we have
reduced energy costs by $1,300 per year for lighting and an additional
$247 per year for air cooling.
See also: Retrofit Economics
How to Calculate Cost of Heating Gains During Heating Season
(in colder climates)
Determining The Cost of Heating Gains During the heating season in colder
climates, the removal of the heat byproduct of lighting system operation
can result in higher heating costs. In most large buildings, the
additional heat would only be needed in the perimeter zone, because the
interior spaces must be cooled all year. This cooling is produced by an
economizer in most buildings.
Rundquist proposes the below formula to determine additional heating
costs:
Extra Heat Required (BTU) = A x B x C ? D
A = Heating Season = 1 ? Fraction of the Year Representing the Cooling
Season Liberal estimate of the heating season, as there are times during
the year when the building is neither heated nor cooled. B = Fraction of
the Lighting Reduction that Has to Be Made Up by Heating A portion of the
lighting heat is released at night. This figure is estimated at 20%. C =
Annual BTU Equivalent of Lighting Saved Lighting reduction in kWh
multiplied by 3,414 British Thermal Units (BTU). D = Seasonal Heating
Efficiency Estimate of basic efficiency of heating system. Heating system
efficiency can vary from about 65-95%, depending on the type, use and
technology. We will estimate 80% for our heating system.
Example: Upgrade of office building in Spokane, WA, resulting in annual
energy savings of 50,000kWh. The average cooling season for Spokane,
according to Table 1, is 15.6 weeks. The heating season is liberally
estimated at 36.4 weeks. The air cooling energy savings comes to
approximately 5,000kWh, or $205 per year.
Extra Heat Required (BTU) = 0.7 x 0.2 x (50,000kWh x 3,414 BTU/kWh) ? 0.8

Extra Heat Required (BTU) = 29,872,500
Extra Heat Required (Therms) = 29,872,500 ? 100,000 = 299
Assuming a cost of $0.9 per therm = $269/year additional heating cost
Net HVAC Savings = $300/year - $269/year = $31/year
Example: Upgrade of office building in Medford, OR, resulting in annual
energy savings of 50,000kWh. The average cooling season for Medford,
according to Table 1, is 21.2 weeks. The heating season is liberally
estimated at 30.8 weeks. The air cooling energy savings comes to
approximately 7,000kWh, or $420 per year.
Extra Heat Required (BTU) = 0.6 x 0.2 x (50,000kWh x 3,414 BTU/kWh) ? 0.8

Extra Heat Required (BTU) = 25,605,000
Extra Heat Required (Therms) = 25,605,000 ? 100,000 = 256
Assuming a cost of $0.9 per therm = $230/year additional heating cost
Net HVAC Savings = $420/year - $230/year = $190/year
Conclusions In a building in Medford, OR, a lighting upgrade generated
$3,000 per year along with $190 per year in net HVAC savings, or a 6%
increase. Not bad. The same upgrade in a building in Spokane, WA, only
increased total energy savings by 1%, or $31 per year in net HVAC savings
added to $3,000 in lighting energy savings. In warmer climates with
longer cooling seasons, and in regions such as the east coast and
California where energy prices are much higher, we can see more
substantial benefits. This same upgrade in Houston, TX or Jacksonville,
FL, would have generated a 26% increase in air cooling energy savings
with fewer losses for heat gains. However, when justifying the economic
returns of investing in the lighting system, every little bit helps.
Capture as many variables as accurately as possible for the given
application to determine net HVAC savings for your lighting upgrade
project.

[Kevin O'Neill]

Man, that's a lot of numbers! I went crosseyed trying to read it!

[behappy]

I went crossed eyed also...... hee hee

Been down this road and relamping to reduce energy works.
but... you have to be careful by reducing lighting to reduce energy.
"The lighting in the area was not as bright and I slipped and fell your honor....

[dan sw fl]

Near useless statement WITHOUT ORGANIZATION

[energy_rater_La]

Guess I'm in the minority here.
I thought it was very important that what works minimally in a heating climate
has a much higer impact on a cooling climate.

(in the last paragraph..)
In a building in Medford, a lighting upgrade generated a 6%
increase.
The same upgrade in a building in Spokane, WA, only
increased total energy savings by 1%
This same upgrade in Houston, TX or Jacksonville,
FL, would have generated a 26% increase in air cooling energy savings
with fewer losses for heat gains.
In warmer climates with longer cooling seasons, and in regions such as the east coast and California where energy prices are much higher, we can see more
substantial benefits.

We talk about one size fits all programs and find fault with them.
But when it comes time to define what works and doesen't work in different climates
& why we seem to be missing details.
This was an attempt to fill in one of the blanks, and have a discussion about
what has been found to work (where and why) as opposed to not attempting
to fill in more blanks.
There is no one size fits all..but there are things that work. Its just to
learn the differences.

Dan,
I'm not sure what you mean by lacking organization?
I took the info from a spread sheet, and document I recieved
and didn't change order of info..sorry if the format is confusing.
Article not organized, or organization presenting study?
Writer's name and company are listed.

[Shophound]

_la,

The issue may not be with the data presented, mainly it is a bit difficult to sift through due to the format, which may be nobody's fault but the way it got posted.

Whenever I see something like that posted I am always interested to hear the thoughts of the one who posted said article/data/etc in addition to the quoted material itself.

My own thoughts are that lighting as a source of internal heat gain is changing as more people adopt CFLs and even LED forms of lighting. Also, CRT computer monitors are on the way out, replaced by flat screen equivalents. The flat screens produce far less heat than the CRT models did. I have heard of some commercial buildings, after undergoing significant relamping to cooler light sources, and phasing out CRT monitors, are now finding interior spaces that utilize cooling only VAV, relying on internal heat gain for reheat, are now requiring addiitonal heat for occupant comfort. Save a few $$ here, spend a few more $$ there to heat a space that formerly did not require heat.

For A/C it's a no brainer. For regions of the country with long cooling seasons, the reduced heat gain during winter months, possibly requiring supplemental heating, is likely offset by the reduced heat gain during the long cooling season.

[jerryd_2008]

Enery_Rater, any way to summarize so that a HO could see the rationalization for reducing lighting heat loads?

PS: Took me some staring to figure out that your "?" means "/" to most math types.