Numerous lighting upgrades have been implemented throughout the Harvard campus using the Green Campus Loan Fund. See the GCLF Lighting Case Studies for more information. New construction projects are highlighted below.

BLACKSTONE (2006) – The 93 linear fluorescent indirect lighting fixtures at Blackstone are equipped with Zumtobel Spheros S T5 lamps.

LANDMARK CENTER (2001) – Landmark Center is using Tridonic Corporation T5 and T8 – 24 and 54 watt lamps.

Only 10% of the energy used in an incandescent bulb is used to create light. The other 90% is emitted as waste heat. Compact Fluorescent Lights (CFLs) are approximately 75% more efficient than incandescents and last 10 to 15 times longer. While CFLs cost about 10 to 20 times more than incandescents, their longer lifetime and higher efficiency give them an average payback of three years or less. CFLs come in either a screw-base ballast, allowing them to be installed directly into an incandescent socket, or “hard wired,” designed specifically for compact sockets.

Linear fluorescent lamps are commonly found in commercial buildings and are even more efficient than compact flourescents. They come in lengths of 4 feet or 8 feet, can have either magnetic or electronic ballasts, and come in a wide variety of fixture boxes.  Linear fluorescent lamps are categorized by their diameter in 8ths of an inch. T12 lamps are 12/8ths of an inch in diameter (1.5 inches), and T8 lamps are 8/8ths of an inch in diameter (1 inch).  T8s decrease energy costs by over 70% compared to T12s, flicker less, have better color, produce twice the amount of lumens and require fewer lamps.  T5 lamps, found at Blackstone, are even more efficient. Replacing T12 lamps with T8 lamps is the most common lighting upgrade at Harvard, as the payback period for their purchase and installation is relatively short.

 

	Lamp and Ballast	Watts per Fixture	Number of Fixtures	Watts per Room	Yearly Burn Hours	kWh per Room	Cost per kWh	Cost per Year
	40 W T12- Elec	188	100	18,800	3120	58656	$0.10	$5,865.60
	28 W T8 - Elect	101	100	10,100	3120	31512	$0.10	$3,151.20

 

Efficacy Comparisons:

 

Cost Comparisons:

 

Light Quality :

 

Even greater savings (in maintenance and energy use) are achieved if the ballast is electronic rather than magnetic.  An 8-foot linear fluorescent lamp’s lifetime can range anywhere from 15,000 to 18,000 hours. In contrast, a 4-foot linear fluorescent lamp’s lifetime is typically up to 20,000 hours.  Electronic ballasts operate lamps 10% more efficiently and cut internal power losses 3 to 8 watts per ballast.  They are less affected by temperature and voltage variations, and eliminate visual flicker.  4-foot linear lamps are also easier to store than 8-foot linear lamps, with less risk of breakage.

 

In existing buildings, upgrades to more efficient lighting not only reduce energy costs, but decrease maintenance costs (fewer replacements) and improve the quality of light.

 

Lighting Terminology: Efficacy vs Efficiency (from the Lighting Research Center)

 

EFFICACY: "IESNA Definition: the quotient of the total luminous flux emitted by the total lamp power input. It is expressed in lumens per watt (lm/W).

 

Lamp efficacy is calculated by dividing lamp lumens by lamp watts:

 

100-W A19 incandescent lamp produces 1740 lm
1740 lm ÷ 100 W = 17.4 lm/watt

 

System efficacy (for ballasted sources) is derived by multiplying rated lamp lumens by the ballast factor and dividing the result by total input watts:

F32T8 lamps produce 2850 lm each on a 2-lamp electronic ballast.
The ballast has a ballast factor (BF) of 0.95, with total input power of 62 W.
(2850 lumens x 2 lamps x 0.95 BF) ÷ 62 W = 87.3 lm/watt.

EFFICIENCY: "IESNA Definition: the ratio of luminous flux (lumens) emitted by a luminaire to that emitted by the lamp or lamps used therein.

 

Luminous efficiency expresses the percentage of initial lamp lumens that are ultimately emitted by the luminaire. The efficiency of a luminaire does not necessarily indicate its effectiveness in delivering lumens to the workplace, or its appropriateness for the application.

 

A porcelain socket, utilizing a 100-W A lamp, has an efficiency of 100%, since no lamp lumens are trapped in the luminaire. A deeply recessed downlight with black multi-groove baffle, utilizing the same 100-W A lamp, may have an efficiency of 70%. Depending upon the application, the less efficient luminaire may be the more appropriate choice of the two, because of reduced glare potential."

 

For more lighting definitions, see the Lighting Research Center: Lighting Terminology

LEDs

Exit signs, though small, use a lot of energy, as they are illuminated 24 hours a day, 7 days a week. Most exit signs cost an average of $35 a year to operate, a cost that can add up in large buildings. Switching to LED exit signs saves $30-$34 per sign per year, and also labor costs, since they do not need to be replaced as often.

 

 

NSTAR has prescriptive rebate forms for Commercial Lighting and Industrial Lighting (summarized below). Mass Electric has nearly the same lighting rebates.

Blackstone average lighting power density for offices is 0.842 w/sq.ft.  (ASHRAE 90.1 is 1.3. w/sq. ft.) Hamilton Hall's lighting power density is U = 1.4 W/sf (ASHRAE is the same).

A comprehensive lighting management strategy can provide significant savings.  The recent renovation of Hamilton Hall used the following strategies, which are estimated to save approximately $2500 in annual operating costs:

• Occupancy control in dorm rooms, kitchen/lounge areas, small conference rooms, bathroom and storage areas
• Night-time setback in hallways, stairs, and main lounge
• Daylight harvesting in stairwells and fourth floor hallway

 

FAS lighting upgrades are saving the department over $712,000 annually and reducing carbon dioxide emissions by over 2.8 million pounds annually through several strategies:

Larry McNeil coupled lighting upgrades with NSTAR rebates to shorten the return on investment. Larry installed 388 occupancy sensors and 182 LED exit signs in Holyoke Center. He also upgraded 131 lamps from T-12s to T-8s at 65-67 Winthrop Street. Lighting upgrades can be excellent investments with short payback periods.

• Finding outside funding for projects (i.e., NSTAR rebates) greatly increases the number of projects that can be undertaken.
• Move quickly and early to secure rebates, as funding for the incentive may run out.
• The Green Campus Loan Fund is an excellent resource for more expensive lighting projects because of their quick payback. For smaller projects, “out of pocket” spending may be preferable.

See case studies of lighting upgrades at HGCI and FAS.

 

Green Seal Recommendations for Lighting Systems

NSTAR Rebates Information and Applications for Efficient Lighting

Lighting Research Center

 

 

BLACKSTONE (2006) – In addition to multiple switching options between compact fluorescent supplemental down-lighting and different combinations of linear fluorescent up-down fixtures, each of the 93 A-type fixtures within 15 feet of the perimeter in regularly occupied space have integrated occupancy sensors, dimming ballasts, and photo sensors. Blackstone uses an indirect/direct lighting cable mounted from the ceiling. Daylight and occupancy sensors are set directly into the fixture. The occupancy sensor turns the light off when the space is unoccupied for more than 20 minutes. Using a DALI (digital addressable lighting interface), the daylight sensor adjusts the light intensity based on a preset level, as daylight changes during the day. The fixture holds T5 fluorescent lamps and digital dimming ballasts for adjustments throughout the day.

 

Occupancy sensors have also been installed as part of lighting upgrades funded by the Green Campus Loan Fund at Soldiers Field Park, Holyoke Center, and KSG Taubman.

 

Advanced Lighting Guidelines – 2003 Edition

The Illuminating Engineering Society of North America (IESNA) Lighting Power Density Models