FREQUENTLY ASK QUESTIONS

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Q1. Does frequently switching on and off of electrical appliances consume more electricity?

A1. "Frequently switching on and off consumes more electricity" is only a misunderstanding. Although it is possible that the starting current of an electrical appliance is higher than its normal current, the duration is very short. Thus under normal use, the additional electricity is negligible. To conserve energy and reduce the impact on the environment, electrical appliances should be switched off when they are not in use.

Q2. Is it a bad habit to leave electrical appliances or computers in standby mode rather than switching them off?

A2. Many modern electrical appliances are designed with standby mode feature, e.g. television and audio equipment with remote control, and computers and photocopiers in the offices which are idling most of the time. If they are not used for a long period, their power sources should be cut or they are unplugged to reduce the standby power consumption. Electrical and Mechanical Services Department has printed a pamphlet on "Reducing Standby Power Consumption" and uploaded to its website. The link is http://www.emsd.gov.hk/emsd/e_download/pee/Reducing_Standby_Power_Consumption.pdf

Q3. How does a T5 fluorescent lamp compare with T8 fluorescent lamp in energy saving performance?

A3. Fluorescent lamp needs a ballast to operate. A T8 fluorescent lamp can be fitted with a traditional electromagnetic ballast or a more advanced electronic ballast but T5 can take electronic ballast only. With the commonly used 1.2m lamp, a T5 with electronic ballast saves 30% compared with a T8 fitted with electromagnetic ballast and saves 10 to 15% compared with a T8 fitted with electronic ballast.

Q4. What should I do if a fluorescent lamp breaks in my house?

A4. Please refer to the guidelines of EPD at https://www.wastereduction.gov.hk/en/household/flrp_faq.htm#faq

Q5. How long will the battery last in my electric vehicle?

A5. Battery manufacturers usually consider the end of life for a battery to be when its capacity drops to 80% of its rated capacity. However, batteries can still deliver usable power below 80% charge capacity, although this will produce shorter range. This means that if your original battery has a range of 100 miles on a full charge, after eight to ten years (depending on how much the vehicle has been driven) this may have reduced to 80 miles. However, the battery will still be usable. A number of vehicle manufacturers have designed the battery to last the lifetime of the car.

Q6. What are the EER and COP of air conditioners?

A6. Energy Efficiency Ratio (EER) is defined as the ratio between cooling capacity (btu/hr) of the air conditioner and its power consumption (W) at a standard rating condition. Higher EER implies better energy efficiency. Typical range of EER is 8 to 10.

Similar to EER, Coefficient of Performance (COP) is also a ratio between cooling capacity of the air conditioner and its power consumption at a standard rating condition. But the cooling capacity and power consumption are expressed in metric unit Watt(W). Higher COP means higher efficiency. Typical range of COP of a residential air conditioner is 2.3 to 2.9.

Q7. Why should we wait at least 3 minutes before restarting air conditioners/dehumidifiers after switching off the appliance?

A7. For those air conditioners/dehumidifiers with built-in compressors, we should wait at least 3 minutes to allow refrigerant pressure to equalize before restarting. Otherwise the restarting current will be too large, leading to excessive temperature rise in the compressors and shortening of their lifetime. For individual model, the instruction manual should be referred.

Q8. Both the air conditioner and the refrigerator are cooling devices. What are their differences?

A8. The air conditioner and the refrigerator operate on similar principles. They both consist of compressors and refrigerants, but have different functions. The air conditioner cools the indoor air for the thermal comfort of occupants. The refrigerator cools its internal space to a lower temperature for food storage, e.g. the fresh food storage compartment is kept at 5 degrees Celsius and the food freezer compartment at -18 degrees Celsius in a 4-star refrigerator.

Q9. Is the air conditioner and the electric fan mutually exclusive? Can the electric fan supplement the air conditioner in delivering cool air, or indeed, can the two complement each other?

A9. Because the electric fan can be positioned at will and can cover a wider angle, it can effectively cover the dead zones for a fixed air conditioner. Using an electric fan with the air conditioner can better deliver cooled air to every corner of the room, creating additional cooling effect in an energy efficient way. Therefore, before lowering the temperature setting of an air conditioner, it is better to use an electric fan as a supplement first.

Q10. What are the energy saving tips of smartphone?

A10. We suggest turning off the smartphone when it is charging at night. When it is not in use, turn off Wi-Fi, Bluetooth and 2G/3G/4G data channel as appropriate. Do not install unnecessary Apps and change the Apps and Email update mode to manual. Besides, do not keep checking the smartphone status.