Green Sense Air Conditioning Survey 2019

About us

Local green group Green Sense has long been paying close attention to urban environmental issues. Multiple scientific surveys have been conducted on both individual and organizational misuse of air conditioning in order to urge Hong Kong to reduce its electricity consumption and carbon emission. Surveys and researches examining air conditioning systems in various transport means and public places such as shopping malls were done throughout this decade.

Research background

According to ‘Hong Kong Energy End-use Data’ 2019 published by the Electrical and Mechanical Services Department, commercial buildings account for 66% to the total electricity consumption, of which 30 percent is used in air-conditioning. Specifically, energy consumption by end-uses in office for air-conditioning accounts for 55%. [1]This reflects that air-conditioner is inseparable with offices.

In addition, studies showed that the temperature in offices affects the working efficiency and productivity, even the relationship among colleagues. [2]However, 40% of workers cannot adjust the temperature in offices.[3]

In order to arouse public awareness in wise use of air conditioning, we recently conducted a survey to investigate whether the air conditioner is probably used, the relationship between the air conditioner and working efficiency, and factors affecting one’s decision to adjust the temperature.


In July and August 2019, we, with the help of volunteers, conducted street questionnaire in 5 commercial districts, namely Central, Admiralty, Quarry Bay, Kowloon Bay, and Kwun Tong. A total of 506 valid responses were collected. All results and graphs are available here.

Major findings

  1. Half of the respondents feel too cold in the office, around 90% of them agree that the temperature affects their working efficiency. (Figure 1)
  2. When feeling cold in the office, 70% of respondents passively adapt to it, which means they wear jackets or drink warm water. Only around 10% of respondents ‘actively take action’ to turn down the air conditioner. (Figure 2)
  3. 60% of respondents cannot adjust the temperature of the air conditioner owing to the central air conditioning system (Figure 3). Among the respondents feeling cold in the office, 65% cannot turn down the air conditioner. (Figure 4)
  4. The outdoor temperature ranges from 29°C to 35°C during the survey. Yet, nearly half of the respondents wore long sleeves. (Table 1)

Table 1

29/7 30/7 1/8 2/8 6/8 7/8 8/8 9/8 12/8
Maximum air temperature 31.4 31.5 27.6 28.5 32.2 33.6 33.5 35.1 34
Minimum air temperature 26.3 26.7 24.9 25.4 32 32.8 27.7 28.1 29.2


Valid responses amounted to 506. The target group of the survey was residents working in the office. Summaries of responses of the 11 questions in the questionnaire are as follows:

  1. (Q1) 50% of the respondents feel “very cold” and “cold”; 42% feel “moderate’; only 8% feel “hot” and “very hot”. This indicates the temperature setting of the air conditioner is too cold, which do not comfort the workers
  2. (Q2) 47% of respondents consider 24-26°C as the most comfortable temperature, which is similar to the government’s proposal of turning the air conditioner to 25.5°C; Following by the option “21-23°C”, which 42% agreed with it. Only one respondent reflects that there is no air conditioner in the office. The results reflect that air conditioners have already been part of our working environment.
  3. (Q3) 86% of respondents’ working efficiency is affected by indoor temperature. From the scale “0” as no effect to “4“ with great effect, 43% of them selected “3” and 25% select “4”. The average is 2.43.
  4. (Q4) When feeling cold in the office, 76% of respondents wear jackets; Following wearing jackets are drinking warm water (24.7%) and turning down the air conditioner (22.9%). Other methods include turning on the heater, using an electric blanket, etc. Turning on the air conditioner while using these devices create wastage of electricity.
  5. (Q5) 11% of respondents had conflicts with colleagues because of the temperature of the air conditioner.
  6. (Q6) Only 40% of respondents can adjust the temperature of the air conditioner. This implies that even feeling cold, they cannot turn down the air conditioner.
  7. (Q7) The major reason for the above situation is attributed to the central air conditioning system (71%). Moreover, 14% and 13% of respondents answered ‘do not know how to adjust the temperature’ and ‘have no authority to adjust’ respectively.
  8. (Q8) The number of questionnaires collected in each district
  9. (Q9-10) The sex and age distribution of the respondents
  10. (Q11) 47% of the respondents wear long sleeves on that day

Conclusion and suggestion

Turning on the air con while wearing long sleeves is definitely a waste of electricity. Global warming is increasingly serious. Hong Kong, as a coastal city, will bear the brunt of global warming in rising of sea level. Therefore, it needs a stronger action to reduce carbon emission. As commercial activities consume the most in terms of electricity, at the same time the use of air conditioners accounts for a high proportion, it could be a way to combat global warming. Reducing electricity usage can even prevent the government to buy electricity from mainland China, which enables Hong Kong to have a more stable and sustainable electricity supply.

With the aim of raising public awareness in reducing the usage of the air conditioner, together with the above findings, the following are some of the recommendations to the government, companies, and individuals.

The Government:

  • Promoting casual dressing to work, like conducting a Pilot Scheme in governmental offices
  • Encouraging companies to participate in the government’s Energy Saving Charter
  • Following the Indoor Air Quality Certification Scheme and IAQ Certification Scheme for Offices and Public Places, encourage companies to comply with the listed standards, like setting the indoor temperature in between 20 to 25.5°C and speed of air movement. Suitable indoor temperature could help improve the indoor air quality


  • For companies using the central air conditioning system, they should reflect the needs to turn down the air conditioner to the property management offices
  • Apart from meeting clients, “smart casual” instead of “formal” dress code is suggested, to reduce the usage of the air conditioner
  • Using fans to assist the air conditioner, which can reduce the electricity consumption of the air conditioner
  • Installing shading curtain, or applying window film to prevent direct exposure to sunlight


  • Actively request for turning down the air conditioner instead of passively adapt to it
  • Prevent the use of heaters or electric blankets to avoid further wastage
  • Drinking water and using mat to reduce reliance on the air conditioner

Follow-up actions

  • We shall continue to examine and monitor the public air con usage, and carry out further studies when necessary.
  • Results of the survey would be widely promoted in our annual energy saving event No Air Con Night along with the message and related information of using air conditioners smartly

No Air Con Night 2019

Until 16th September, 13 universities and tertiary institutions, and 224 kindergartens, primary and secondary schools (102 kindergartens, 85 primary schools, and special schools and 37 secondary schools) have registered to participate in No Air Con Night 2019. Participating institutions have also promoted this green event on their campuses. In addition, more than 190 companies and organizations, as well as 700 properties have joined the event and agreed to promote it with full efforts among their employees.

We are now inviting various public figures to participate in the event to encourage the public. This year we are happy to have Mr. Mok Ho-kwong of Natural Network, influential travel writer Mr. James Akio Hong. We are also inviting LegCo members and district councilors to participate and motivate the public to turn off their air con at night.

On 5th October, it will be our 10th Anniversary Special: The Day and Night of No Air Con. the activity will start from 1 pm to 9 pm in Vessel 01, Kwun Tong Promenade. Bunch of interesting activities including workshops and workout classes will be held for the public to enjoy in an air con-free environment. We welcome all to turn off their air con, head out to Kwun Tong and have a great night at the promenade.

For more information about no air con night and energy-saving: http://greensense.org.hk/noaircon