How do we calculate the Ecological Footprint of Hong Kong in 1997?

The basic concept of Footprint calculation has been discussed in the introduction section of Ecological Footprint. Let's explore more details in this section!

The above figure is an example of how we calculated Hong Kong's 1997 Food Footprint, which we have done for all of the 5 sectors. Can you see how complicated and data-intensive is the calculation process? Do you know what is counted and what is not?


Let's use Energy as an example to demonstrate the calculation process. The Energy Footprint sums up the energy consumption in producing energy, water, food, material and urban. What are included in each of these categories are described as follows:

1. Energy consumption in producing Energy

2. Energy consumption in producing Water

3. Energy consumption in producing Food

4. Energy consumption in producing Material

5. Energy consumption in producing Urban


After we identify all the production processes, we then go into trade statistics and extract the relevant figures for calculation. After we calculated the consumption level of each of the 5 sectors, we then converted the unit into hectares by using the following:

1. Energy
Using 1TJ of fossil fuel would emit 18 metric tons of carbon each year, and 10 hectares of forest would be needed to absorb this. Thus, the conversion factor is 10 forest hectare per 1TJ of energy consumed.

2. Water
We do not convert water use into land area but rather keep the unit in cubic metres (i.e. 1000 litres). The Footprint is calculated as: (m3 water taken - returned)natural. By using this, recycled water is viewed as being used but not taken from nature, and if the used water is returned to nature in its original, natural state (i.e. free of any chemical, organic or thermal pollution), then this is subtracted from the water footprint.

3. Food
The size of the Food Footprint is converted from food consumption by this equation: , where crop yield factor are taken from the United Nations Food and Agricultural Organisation (FAO) database. .

4. Material
Material Footprint comprises two parts, namely the Extraction area and the Accumulation area. Extraction area refers to the area that provides renewable materials like cotton. Accumulation area refers to the area that absorb the un-recycled waste products and contaminated land. The size of the Footprint is the addition of the two areas.

5. Urban
The Urban Footprint consists of three parts: 1. The developed area of our city; 2. The developments outside HK used to process our resources (imported city); and 3. Land disturbed by the extraction and processing of materials, i.e. mining. The size of the Urban Footprint is the addition of the three areas.

Below are sample calculations of the footprint of a Food product (USA frozen chicken) and a Material (steel). Please contact us for more details of the calculation procedures.



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Reduce paper use and promote paper recycling
If fewer trees are cut down to produce paper, we will have more trees to absorb CO2 which is the gas implicated in global warming.
少砍伐樹木, 幫助減低溫室效應. 據資料顯示, 每公頃森林每日能吸收一公噸的二氧化碳, 放出0.73公噸的氧氣.

Choose electrical appliances with an Energy Efficiency Label
改用能源效益標籤屬於第一級別的電器, 可大大減少電力消耗. 第一級別的雪櫃比普通雪櫃省電35%, 儲水式熱水爐可減少25%耗電量, 第一級別的洗衣機則可以減少用電20%等.

Energy saving
Make sure all your electrical appliances are switched off, instead of just being in standby mode, when you leave the room
睡覺前把不用的電視, 電腦, 微波爐等電器的電源關上, 比起設於備用狀態更加省電.

Keep the room temperature at 25.5 C
Electricity consumption is lowed by 1.5% for every degree Celsius increase in the thermostat
原來每調高1度空調, 一年可以節省1.5%耗電量

When you order a take away,
bring your carrier or reusable container. This helps to reduce non-biodegradable Styrofoam packaging.

Promote paperless office
Promote a paperless office by sending send emails instead of mail and link up your computer network, as this cuts
down on the need for printing jobs which will save paper. Reuse computer print-out paper as memo pads or telephone message pads.

Reduce Water Consumption
When brushing your teeth, use water in tumbler instead of from a running
tap. Take a shower instead of bathing
in a bathtub. Install a dual-action flush in your toilet to reduce
water consumption.

Enjoy natural resource
It's better to rely on natural and ventilation. Leave windows open and switch off the lights and fans which are not in use to reduce energy consumption.

Green consumption
Plan your shopping list to avoid over-consumption, which normally contributes
to household waste. Instead of ending up with many plastic bags, bring your
own shopping bag to hold smaller items. This eliminates unnecessary
consumption of plastic bags and reduces waste.

Say Yes to Public Transportation
Public transport can usually take more people at a time to their destinations,
which reduces your energy consumption. You can also consider
other means of transportation, such as a bicycle or simply go on foot if
possible.

Plants are great!
Growing plants can creat a pleasant working and living space. In additional, they can
also serve as an air purifier and give us all healthier surroundings.