Energy Conservation

As per Wikipedia, energy conservation refers to reducing energy through using less of an energy service. Energy conservation differs from efficient energy use, which refers to using less energy for a constant service. For example, using a bulb for lesser hours by using daylight is an example of energy conservation, but replacing it with CFL and using for same hours is efficient energy use. Energy conservation and improving energy efficiency are both energy reduction techniques. Energy conservation can be done by reduction in wastage of energy.

The economic development of a country is closely linked to its consumption of energy. So we have to use energy, but we can use it efficiently. India’s energy intensity (Energy consumption per unit of GDP) is high, it is higher by 3.7 times of Japan, 1.4 times of Asian average, and 1.5 times of US. This shows high wastage of energy and low energy efficiency, but at the same time, very high energy saving potential.

Table of Contents

Importance of Efficient Use of Energy and its Conservation

  • Coal and other fossil fuels, which have taken three million years to form, are likely to deplete soon. In the last two hundred years, we have consumed 60 % of all resources. For sustainable development, we need to adopt energy efficiency measures.
  • Today, 85 % of primary energy comes from non-renewable fossil sources. These reserves are continually diminishing with increasing consumption and will not exist for future generations.
  • With the increase in GHG emissions, global warming is increasing.
  • It is particularly important for a developing country like India in view of limited energy resources and the increasing gap between demand and supply. It will lead to reduction in energy imports, and in capacity addition. One unit at the consumption level avoids 2.5 to 3 times fresh capacity addition. It has been estimated that improving energy efficiency and demand side management measures can save nearly 25 000 MW capacity addition.
  • The energy cost is a major component of the operating cost in an organization and employing energy efficient techniques can significantly bring down the operating cost of any organization and increase its productivity, profitability and competetiveness.

Tips/Methods for Efficient Use of Energy and its Conservation

Electrical energy is utilized in building in various ways such as lighting, ventilation, pumping, air conditioning and lifts etc. Given below is the conservation and energy efficiency improvement tips:

Lighting

In India 8 to 12 % of electricity is used by domestic lighting, commercial and street light. India has about 1 billion lighting points. Here lighting represents about 30 % of the building’s energy consumption and so a remarkable saving can be achieved

Energy Conservation Tips

  • Switch off the lights if the room is unoccupied or when it is not needed. Post the reminder stickers for turning off light near exit points. Start awareness programme.
  • Clean luminaire and inner room surfaces periodicaly. This enhances illumination by 15 to 20 %.
  • Avoid unnecessary high illumination by switching-off, declamping or removing one lamp from dual lamp luminaire. It not only consumes more energy but also generates thermal load.
  • Avoid decorative fittings as far as possible.
  • Use daylighting, wherever feasible. Use light-coloured, loose-weave curtains on your windows to allow daylight to enter. Also, decorate with lighter colours that reflect light. Shift work area near to windows.
  • Use task lighting as for as possible. A reading lamp, for example, lights only reading material rather than the whole room.
  • Lower the liminaire.
  • Keep system voltage at standard and optimal level.
  • Think of putting off neon bulbs and flood lighting after 11 PM.
  • Keep the colour of walls and ceilings as much light as possible, considering the aesthetics and utility.

Energy efficiency methods

Energy efficiency can be improvement in two ways:

  • Replacing standard lamps and conventional gears with energy efficient lamps and/or HF ballasts in existing lighting installations.
  • Renovate lighting installation.

Though re-dooing the lighting installation normally generates the highest energy saving, but even changing the lamps/control gears can lead to significant cost reductions. Lighting controls give a greater choice in efficient energy use while retaining the lighting effects.

  • Replace incandescent lamps with CFL or flourescent tube. A 60 W incandescent bulb can be replaced with 15 W CFL, while giving same light. Morever, almost 90 % energy is given off as heat in incandescent lamps, increasing thermal load.
  • Replace T-12 (40 W / 20 W) tubes with T-8 (36 W / 18 W) or T-5 (28 W / 14 W) tubes.
  • Replace luminaire with mirror optic luminaire.
  • Replace halogen lamps with compact HID lamps, if colour rendering permits.
  • Replace HPMV lamps with HPSV / metal halide lamps, as per colour rendering requirements.
  • Replace old exit signs with new LED signs.
  • Install solar powered compound light.
  • High frequency (> 2 kHz) electronic low loss ballasts saves energy to the tune of 30 to 40 % compared to conventional Copper ballasts. A tube light with copper ballast needs power of 55 W compared to 36 W for one with electronic ballast.
  • Provide automatic devices like occupancy or motion sensors, light sensors, automatic or astronomical timers, for switching the lighting when required.
  • Provided dimming, which can be used either manualy or be integrated with daylight sensors to dim the lighting system according to daylight available.

Fans

Energy conservation tips

  • Mass awareness should be inculcated towards energy conservation and it should be made habitual to switch off the fan if not needed of if room is unoccupied.
  • A periodic maintenance should be observed for cleaning, oiling and replacement of defective bearings, if required at the earliest.

Energy efficiency methods

  • Replace conventional regulator with electronic regulator when fans are not required to run on full speed. Table of energy saving is given below:

    Speed StepResistance RegulatorSolid State Regulator% Power SavingIncrease in VA
    VMTWINPFVMTWINPF
    1108451.0128250.46344.4216
    2126541.0147350.55635.2179.9
    3142580.999166440.63124.1158.5
    4164640.998185550.76414.0130.9
    5222780.996221780.996--

Computers

Energy conservation tips

Computers consume significant energy as mostly they are kept on. A desktop PC may be rated from 60 W - 250 W, while a laptop is rated from 15 W - 45 W, depending on configuration.

  • Turn off your computer after use. A computer (100 - 150 W) that is kept on 24 hours a day, uses more energy than an energy-efficient refrigerator.
  • If your computer must be left on, turn off the monitor; this device alone uses more than half the system's energy.
  • Setting computers and monitors to use sleep-mode when not in use helps cut energy costs by approximately 40 %. Use built in power management feature.
  • Battery chargers of laptop, tablet, mobiles, consume energy whenever they are plugged in and are very inefficient. Pull the plug and save.
  • Screen savers save computer screens, not energy.
  • Start-ups and shutdowns do not use any extra energy, nor are they hard on your computer components. In fact, shutting computers down after use actually reduces system wear and saves energy.

Energy efficiency methods

  • Use LCD screens. The power of 17" CRT is 75 W and of 19" CRT is 100 W compared to 30 W for 17"/19" LCD. Also LCD run at lesser temperature and so saving in AC will also be there.

Air Conditioning

AC systems consume 50-60 % of total energy in a commercial building, thus having huge potential for reduction.

Energy conservation tips

  • Use fans as first line of defence. They consume less energy. Also using fan with AC allows better circulation of cool air and temperature setting can be kept higher.
  • Keep the thermostat of room air conditioner at 25 °C for comfort cooling, at least cost. Each degree of setting above 22 °C gives uses 3 to 5 % less energy. For other applications, keep appropriate thermostat setting.
  • Control the cooled air flow through dampers and when the room is likely to be unoccupied for longer duration, the conditioned air flow to room should be cut-off.
  • Partition off the area where cooling is not needed.
  • Switch off AC unit about half an hour before the office closing time. The rooms will remain comfortable for this duration.
  • Keep doors to air-conditioned rooms closed.
  • Do the preventive maintenance for equipments, AHU, pumps, fans etc.
  • Clean coarse and fine filters every month. A dirty air filter reduces airflow and may damage the unit. Clean filters enable the unit to cool down quickly and use less energy.
  • Clean cooling & condenser coil periodically and comb mashed fins.
  • Remove obstructions in front of condenser, if any.

Energy efficiency methods

  • For designing of AC system, tendency of specifying high ambient temperature may be avoided. This not only costs higher, but also causes more energy consumption. Summer outside design conditions have been brought out by BIS (IS 7896 : 1975) and it should be used.
  • Provide sun control film on the glass or use tinted glass or double glazing. Glazing area should be provided for enough daylight, but not at the cost of heat load addition.
  • Insulate room and roof, if viable.
  • Efficient lamps in airconditioned area decreases the heat load. However, they should be provided with proper luminaire as temperature is low and luminous efficiency of fluorescent lamps may be less.
  • Very old chillers of Central plants may be replaced by new chillers as old chillers consume more energy since their heat transmission coefficient has gone down. Proper softening plant should be installed and seen that it is operative, since the scales on condenser reduces its heat transmission coefficient. Chilled water pump operating time may be reduced.
  • Central plants including water cooled package units are highly energy in-eeficient and they should be surveyed and replaced with energy efficient Package AC units. Heating and humudufication circuits should be put off. Micro-processor based control system may be developed and adopted to optimize energy use.
  • Examine the efficiency of old AC units and replace with energy efficient one, if required. Also follow the same procedure during major repairs. For a 1.5 TR unit running 1600 hour annualy, a BEE 3 star AC will save 425 unit, while 5 star unit will save 750 units as compared to 1 star unit. The payback period is typically 3 years.
  • Use "Free Cooling" in cold weather.
  • Desiccant drying of outside air to reduce cooling requirements in humid climates.

Refrigerators

The power rating of small refrigerators is 225 W and that of bigger ones is 300 W. So choose the size of refrigerator considering requirement and family size.

Energy conservation tips

  • Set thermostat in medium cooling position.
  • Refrigerator motors and compressors generate heat, so allow enough space for continuous airflow around refrigerator. If the heat can't escape, the refrigerator's cooling system will work harder and use more energy.
  • Do not overstuff refrigerator, allow adequate air circulation inside.
  • Think about what you need before opening refrigerator door. You'll reduce the amount of time the door remains open.
  • Allow hot and warm foods to cool and cover them well before putting them in refrigerator. Refrigerator will use less energy and condensation will reduced.
  • When dust builds up on refrigerator's condenser coils, the motor works harder and uses more electricity. Clean the coils regularly to make sure that air can circulate freely.
  • For manual defrost refrigerator, accumulation of ice reduces the cooling power by acting as unwanted insulation. Defrost freezer compartment regularly for a manual defrost refrigerator.
  • Make sure that refrigerator is kept away from all sources of heat, including direct sunlight, radiators and appliances such as the oven, and cooking range.
  • Make sure your refrigerator door seals are airtight. When it's dark, place a lit flashlight inside the refrigerator and close the door. If light around the door is seen, the seals need to be replaced.
  • Cover liquids and wrap foods stored in the refrigerator. Uncovered foods release moisture and make the compressor work harder.

Microwave Ovens

Energy conservation tips

  • Microwaves save energy by reducing cooking times. In fact, one can save up to 50 % on your cooking energy costs by using a microwave oven instead of a regular oven, especially for small quantities of food.
  • Remember, microwaves cook food from the outside edge toward the centre of the dish, so if you're cooking more than one item, place larger and thicker items on the outside.
  • Don't open the oven door too often to check food condition as each opening leads to a temperature drop of 25 ºC.

Washing Machine

The power rating of fully automatic washing machines ranges from 325 W to 1 100 W and those of semi-automatic is 200 W.

Energy conservation tips

  • Run washing machine only with full load.
  • Use optimal quantity of water.
  • Use timer facility to save energy.
  • Use hot water only for very dirty clothes.
  • Always use cold water in the rinse cycle.

Electric Iron

The power consumption of domestic iron ranges from 450 W to 700 W, while heavy duty irons are rated for 1 000 W or more. So, while purchasing, select iron with automatic temperature cut-off.

Energy conservation tips

  • Use appropriate regulator position for ironing.
  • Do not put more water on clothes while ironing.
  • Do not iron wet clothes.

Water Heaters

The typical 25 litres storage type geyers is rated for 2 kW and raises temperature by 35 °C and takes about 30 minutes in doing it. It needs 2 cycles i.e. one hour approximately to heat about 100 litres considering that not all 100 litres need to be raised to 35 °C. So per month unit consumed is 60 units.

Instant water heaters is are typically rated 3 kW - 4.5 kW. A 4.5 kW heater raises temperature by 21 °C at a flow of 3 LPM and heating 100 litres takes about 30 minutes. So per month unit consumed is 67.5 units.

Energy conservation tips

  • Switch off when not required.
  • By reducing the temperature setting of water heater from 60 °C to 50 °C, one could save over 18 percent of the energy used at the higher setting.
  • To help reduce heat loss, always insulate hot water pipes, especially where they run through unheated areas.

Pumping

Energy conservation tips

  • Water leakage should be minimised or stopped if possible. Proper rationing of water and its timing may be fixed.
  • Repair, seals and packing of pumps to minimize waste.

Energy efficiency methods

  • Tendency of oversizing a motor while designing a pumping installation should be shelved out. An oversized motor operates at lower power factor, low efficiency and also costs more. Energy efficient higher power factor motors should be used.
  • Since the pressure drop through gate valve is considerably less than that of a globe valve, controlling water flow through globe valve should be avoided.
  • Normally water piping is designed on velocity consideration, but friction losses for smaller diameter pipes are very high. So smaller diameter pipes should be designed based on pressure drop consideartion, for larger pipes velocity considerations are in order.

Sub Stations

Energy conservation tips

  • Set transformer tap for optimum loading.
  • Disconnecting primary of standby transformer.
  • Balance 3 phase loads.
  • Check of efficiency after rewinding of transformer and motor.

Energy efficiency methods

  • Improve and maintain power factor by providing automatic PF correction system. This will also result in incentive and will avoid penalty.

Engine Alternators

Energy conservation tips

  • Oil bath air cleaner and clean / replace air filter timely.
  • Use proper grade and manufacturer recommended lub oil.
  • Replace lube oil filters timely.
  • Maintain lube oil level & pressure.
  • Timely replacement of fuel filters.
  • Calibrate fuel injector.
  • Temperature to be Maintained within range.
  • Optimal engine loading corresponding to best operating point is desirable for efficiency.
  • Balance 3 phase loads, as unbalance loads cause more heating in alternator.
  • Maintain power factor. Alternator is designed for 0.8 PF lag. Lower PF demands higher excitation currents and results in increased losses.

Lifts

Energy conservation tips

  • In a building having more than one lift, staggered floor serving should be implemented to reduce the number of starts and stops.
  • Do periodic maintenance of ropes, sheaves, bearings etc.

Energy efficiency methods

  • Replace old and inefficient motors with high efficiency motors.

Conclusion

  • Use of energy efficient lamps should be promoted along with electronic ballast.
  • Use of proper design of ventilation should be inculcated.
  • Motors, transformers etc should not be allowed to run lightly loaded and should be surveyed with low capacity transformers.
  • Periodic maintenance schedule should be developed, followed and adhered to.
  • Very old energy deficient equipments should be changed phasewise.
  • As far as practicable higher RPM machines should be used.
  • Optimum voltage should be used. Higher voltage increases the magnetizing current and thus decreases the power factor.
  • Have a building management systems for integrated energy control.
  • As far as possible use renewable energy.

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