Every time I step into Hui Fai's farm, pad along the grass and down a narrow tree-lined path to the main field where a dozen vegetable species grow, I am grateful that my job is always about meeting interesting and courageous individuals.

Ah Fai is an organic farmer. The Canadian-born Chinese spent 12 years working as an executive in the technology and finance industries. He impresses me not only because he quitted a high-flying life in Central to become an organic farmer in Fanling, but I also admire his determination to make sustainable farming practicable. Local organic farms are receiving more and more attention, whether at the consumer level, or as an alternative way of life that they represent. The fact that this tough, toilsome and financially unrewarding job is attracting even the young and university-educated is proof that, for some, organic farming is hip. Ah Fai is unique, however, because he enjoys working alone and unnoticed at the farm. The 41-year-old is constantly looking at how he can advance his farming knowledge and skills, and he upholds the philosophy of organic farming while embracing inventive branding techniques when it comes to selling vegetables.

"My struggle is am I making the most improvement? What if I am not studying hard enough, not working hard enough? Most people think I am an idiot but I have my own objective. I want to make as much improvement as possible. In the past, when I met my friends, what did we talk about? The stock market, the property market, what do you think about the economy, is it going up or going down? How about that bar you went to last night? I don't find these topics very interesting," Ah Fai said.

Now he travels between home and his farm on a bicycle. He works six hours a day and studies for several hours in the evening. When he talks, it is always about weeding, watering, ploughing, seeds, seedlings, composting, the soil, the weather, and the different experiments he has been doing on each soil bed. His passion may be overwhelming, but he's always able to draw me into every aspect of his farm with the charm and effortless ease of a raconteur.

Ah Fai is very conscious of the carbon implications that each and every of his actions brings to the world. Playing a more active role to reduce carbon emissions in the face of climate change is the major reason that has turned him to organic farming. He says organic farming is therefore not just about excluding synthetic fertilizers and pesticides to avoid soil and water pollution because for it to be sustainable, it should include growing food locally, so that what we eat doesn't have to travel long distances and create unnecessary carbon emissions before it reaches the dining table. For this thoughtful farmer, responsible farming also ensures that insects and other forms of life are not killed just because human beings need to grow food.

As a matter of principle, Ah Fai only grows in-season vegetables and he does not use a green house. He divides his 8,000 square-feet farm into a dozen of smaller plots and rotates their use so that the soil will have time to rest and recover. He experiments at each plot of land to find out the optimal combination of soil, seeds, nutrients, water, as well as the precise timings that go with each factor. Aubergines, broccoli, beetroots, bell peppers, cherry tomatoes, corn and kai-lan grow side-by-side. There's no farm machinery in sight because it is the biggest carbon emitter. Therefore ploughing, one of the most energy and time-consuming activities on the farm, is completely manual.

"Everyone uses a ploughing machine, I don't have one. Nobody grows like this. What I am doing is 10 times more time-consuming than using a machine, and this plough is very heavy. Then there's weeding, farmers in Asia squatting down, using knives to uproot the weeds. But this position is very tiring. You can't do this for long unless you're a farmer for 20 years. I am a beginner; I need to find the right tool that fits my body and the land."

He wants to modernise the plough. He also wants to improve the weeding method and the tools involved. Moreover, he wants to innovate many other manual implements that farmers pass from one generation to the next without ever questioning their efficiency. He uses the example of tennis and badminton rackets that are made of carbon fibre to make his point. "Over the past 20 years, the rackets have dramatically improved. You can hit harder and faster with the same amount of human energy because the tool improved. Why can't we use carbon fibre to make farming tools?"

Ah Fai is working with a farmer-turned ironsmith to tailor-make the right tool for himself. The first product is a plough-like weeding tool which will allow him to weed his crops standing up. The second creation is an improved cart with two large wheels which makes it easier to balance and push around in the field, and the low handle design means it doesn't even have to be lifted when in motion. He also uses stackable crates so he can load and unload things more efficiently. Ah Fai compares the impact of his inventions to the benefits of a bicycle. "A person is very slow; a car is very fast but consumes a lot of energy. The best option is a bicycle. The energy use is the least for going a long distance."

Ah Fai's efforts to minimise carbon footprint doesn't mean he sells his vegetables without packaging. He packs different vegetables together, playing on their contrasting, or complementary colours. He wraps them in the kind of raw-looking paper that Thai food vendors use to pack their cooking. "The reason farmers can't get ahead is because they are not good at branding and packaging. An eggplant is unable to distinguish itself from another eggplant, so we need design to add value through packaging. Actually, packaging is important because the vegetables need protection to stay fresh." The ever-enterprising farmer has also started a 'dining at the farm' programme. Calling it 'Farm-to-table', it's designed for city-dwellers who want to harvest vegetables from the field and eat them fresh at the farm.

None of the farm's commercial activities bring in a profit, but Ah Fai is not bothered. "The farming industry makes money but the farmer doesn't. I don't need to make money now. How much money I could make anyway compare with my old job? What I care is whether I am progressing. It is why I am experimenting. As long as I keep improving, eventually I can scale it up. I don't think of how far I can go. I am trying my best and I enjoy the process."

Ah Fai may prefer to focus on the process rather than an end result, but he's driven by the belief that his actions are laying the groundwork for a revolution in how we consume food: "If enough people start eating organically, one day, we can displace conventional farming."

I met Rachel because she wrote to me. She was responding to a newspaper article on food banks that I filed for a former employer, the South China Moring Post. "Food banks may provide food aid to the poor, but the right solution should include saving tonnes of wasted food from supermarket chains, restaurants and hotels, and passing them to the hands of the needy," Rachel told me.

She included in her email information on a programme that collected vegetables discarded by hawkers at Tai Po's Po Wu wet market and turned what's otherwise destined for the landfill into delicious meals for a group of unemployed. Rachel hoped I could introduce this programme to the public and make the issue of food waste more visible. This was long before civil society began to take on the supermarket chains for dumping – and effectively destroying – food that is still edible.

However, what impresses me about Rachel, and has made us friends, is her one-person carbon reduction enterprise: a highly successful clothes recycling project known as "Adopt Me".

Rachel is a lawyer specialising in intellectual property rights. When we met for the first time in the summer of 2011, the straight-talking lawyer, whose office is in Central's Jardine House, had gone 18 months without shopping for a new outfit. As a green enthusiast, she believes the only way to save the planet from human destruction is for individuals to cut their energy emission, and that includes not falling into the trap of endless consumption.

Her one-person green enterprise started with a causal conservation. "There is this friend, she is addicted to shopping, so I said, 'why don't you give me what you no longer wear?' Soon afterwards, she came with a suitcase of outfits, they are new. Inside the suitcase, there were also French-made leather handbags – I'd never had one of those before," Rachel said.

Since then, she accepts "out-of-vogue outfits" from her friends and their friends. As the word spread that Rachel had generously gone on a mission to help others free up precious wardrobe space, she started to accumulate more fashionable and nicely-tailored clothes than she needed, and this is how her "Adopt Me" programme began.

Whether it is a blouse, a dress, a skirt, a suit or a pair of pants, Rachel measures and photographs them. Later, she tells her friends and acquaintances to check out her latest collection on Facebook. If an outfit takes their liking, Rachel will deliver it by post, or personally. She doesn't charge for the service, and her customers don't even have to pay for the postage. The fashion stocks are stored in her office and her three-bedroom apartment in Fanling.

More storage space was needed as the stocks grew. Rachel and her husband Hui Fai moved to Fanling in April 2011 following the latter's decision to change profession from an IT consultant to a full-time organic farmer. Living in Fanling allows them to stay close to the farm. Fai usually cycles to the farm while Rachel goes to work in Central on the train. With a bigger apartment, Rachel has more space for her collection.

To date, she has given away more than 300 outfits, and her expanded service now also covers male outfits, kids wear, handbags, shoes and accessories. The "Adopt Me" Facebook page has given way to a blog that the couple runs together. The blog promotes responsible consumption, on top of the "Adopt Me" programme, and the husband-and-wife team also uses the site to review reasonably-priced vegetarian restaurants, green products, books on the environment.

Rachel has no plan to charge for the clothes adoption service. "This is what I should do, it is my little part on easing climate change," she said. But as the popularity of "Adopt Me" continues to grow, Rachel is struggling to keep up with the constant stream of new customers and donors. "There are dozens of new arrivals still waiting to be measured and have their photo taken. If my customers find that there are no new stocks, it is because I haven't got time to update the collection on my blog."

Equally, Rachel has no time to entertain the workings of consumerism, and that's what's giving her the determination to continue her modest but significant planet-saving campaign. "Shopping culture is a scam created by the big capitalists. In order to get the hard-earned cash out of our wallet, they use manipulative advertisements to play around with our vanity, creating a culture in which having a particular handbag will make us the envy of everyone. By packaging the money-making business as art, the capitalists get richer. Consumption is just something shallow once we see through the gimmicks," she said.