• Blog Posts
  • Halogen vs. LED: comparing lamp surface temperature and its influence on room temperature

Halogen vs. LED: comparing lamp surface temperature and its influence on room temperature

  • Posted in Default
  • By admin
  • Date September 28th, 2012 17:02
  • Follow
  • The Chinese government made waves by requiring that 30% of all new construction be built green by 2020. Since, subsidies have been released to incentivize the market to respond.  On September 15, 2012 RMB 6,000,000 subsidies became available for energy efficient projects. We recently ran a test pilot at our office to measure the impact that lighting has on room temperature, and thus energy consumption. It is easy to calculate the energy saved when using lamps, though the heat produced by lighting sources is rarely discussed. Our pilot tested both Halogen and LED MR16 lamps to measure the impact each had on room temperature. 

    Halogen lamp: is an incandescent lamp that includes a small amount of halogens (such as iodine or bromine).  The combination of halogen gas and tungsten filament produces a halogen cycle chemical reaction which redeposits evaporated tungsten back on the filament, increasing its life and maintaining the clarity of the lighting envelope. Because of this, halogen lamps can be illuminated at higher temperatures than standard gas-filled lamps of similar power and operating life, producing light of relatively higher luminous efficacy and color temperature. The small size of halogen lamps permits their use in compact optical systems for projectors and illumination. The efficiency of halogen lamps approaches 12~15 lumens/W. Halogen lamps have life spans around 2,000 and 3,000 hours.

    LED lamp: is a solid-state lamp that uses light-emitting diodes (LEDs) as the light source. The efficiency of LED lamps ranges between 100~120 lumens/W. LED lamps have life spans around 30,000 to 50,000 hours.

    Space: 1.64m x 2.95m x 2.65m (12.8 m3). 

    Date: Sep.17.2012

    Subjects: 2 Halogen MR16 lamps (various brands):    12V 35W

                        2 Electronic transformers:   In 220V - Out 12V      20-50W 

                        2 LED lamps:etrilum MR16 lamp    220-240V 7W

    Tools: 1. Fluke 59 Mini digital thermometer (Measurement Range: -18°C to 275°C)

    2.  A suspended piece of A4 paper, used to measure surface temperature. Paper lacks thermal mass; its surface temperature also represents ambient air temperature. 

                3. Scotch tape (used to suspend the paper). 

    Procedure: 

    1. Suspend the paper 0.3m below the lamps and measure the temperature of the lamps and the paper before the lights are turned on.
    2. Turn on the lights,  then measure the temperature of the lamp surface and the paper every 5min,15min, 30min, and 60min.
    3. Replace the halogen lamps and electronic transformers with LED lamps, then measure the temperature of the lamps and the paper before the lights are turned on.
    4. Repeat steps 1 & 2.

    Data Sheets: *Room temperature: 22°C to 25°C                                                                         (Unit:°C)

    Halogen lamps

    LED lamps

    TIME

    LAMPS 

    PAper

    TIME

    lamps

    paper

    9:40

    27.0

    21.8

    14:10

    27.9

    27.0

    Lights on

    Lights on

    9:45

    264.2

    28.6

    14:15

    67.2

    27.4

    10:00

    248.8

    30.0

    14:30

    81.8

    28.0

    10:30

    253.3

    30.2

    15:00

    82.0

    26.8

    11:30

    263.2

    30.4

    16:00

    82.2

    26.8

    Ave.T

    257.4

    29.0

    Ave. T

    78.3

    27.3

    Temperature differential

    7.2

    Temperature differential 

    0.3

    Synthesis of Results:

                    The halogen lamps surface temperature (257.4°C) is triple that of LED lamps (78.3°C);

    The halogen lamps have the greatest impact on room temperature, increasing room temperature by 6.9°C more than LED lamps. In Shanghai’s cooling dominant climate, this increased heat must be offset  by mechanical conditioning systems, meaning the efficiency of lighting cannot be measured solely by the energy consumed for illumination. Systemic impact on conditioning systems must also be considered. In our case, temperature increases are offset by a stand-alone air conditioning unit. 

    Brand

    Meidi

    Model

    KFR-72LW/DY-GC(R3)

    Number

    3P

    Type

    Auxiliary electric heating

    Constant-speed /Variable-frequency

    Constant-speed 

    Energy efficiency grade

    3 of 5

    Cooling input

    2338W

    Cooling capacity

    7200W

    E.E.R

    3.08

    In general, the power consumption of constant speed ACs can be measured by dividing the cooling input by 1000 (cooling input/1000). Our AC’s cooling input is 2338W, thus its power consumption per hour = 2338/1000 = 2.338 kWh (much greater than either of the lamps!). Regardless of the temperature set, the cooling input will always be 2338W when the AC unit is operated. Certainly, larger temperature increases require longer conditioning periods. Have a second look at the testing results. The test was conducted on a relatively comfortable day, with temperatures below the common threshold for comfort (26°C). The Halogen lamps brought the room temperature above the threshold of comfort, whereas the LED lamps had a non-perceivable impact on thermal comfort. 

    In cooling constant climates, there are no additional energy efficiency benefits to sourcing LED lamps over Halogen lamps (beyond their inherent energy efficiencies).  Though, in warm climates that fluctuate between comfortable and uncomfortable, selecting lighting that generates additional heat compounds the need for conditioning and energy consumption. Energy savings can be recouped even faster if appropriate lighting is selected. Feel free to contact us with your specific lighting questions. 

     Appendix:

    1. The Lamps pictures 

     

    

     

     

     Halogen lamps and Electronic transformer 

     

     etrilum LED lamps 

     

     

     

     

     

     

     2. The Lamps pictures during the experiment 

     Halogen lamps  

     

     etrilum LED lamps 

     

     

      3. Fluke 59 Mini digital thermometer 

     

     

     

Loading...
×
server error: