The wind turbine erected in front of this otherwise unremarkable, one-storey building in Si Racha tends to grab the attention of passers-by, its function in attracting customers a useful bonus for its owners, Tesco Lotus.
The international supermarket chain had good reason to be proud of this spanking new store, but plans to give it a grand launch with much fanfare were shelved because of the floods preoccupying the nation late last year and the store, the first "zero-carbon" supermarket in Asia, had a rather muted opening on November 25.
Located on a 1,200m2 site on Bang Phra Road on the outskirts of this small seaside town in Chon Buri, the supermarket was purpose-built using some costly, high-tech materials into order to achieve the goal of zero net emissions of carbon dioxide. The task of monitoring CO2 emissions from the store's lighting, air-conditioning and refrigeration systems has been given to an independent outside contractor.
The sales floor is relatively modest at 7002, the remaining space on the site being used for a waste-water management plant, car park and power generation: that prominent wind turbine plus a small solar-cell "farm" located at the rear of the premises.
"This is the very first zero-carbon store in Thailand, and in Asia for that matter, and only the third one built by the company anywhere in the world. The others are in the UK and the Czech Republic," said Prasert Kamthornkittikul, senior facility manager (energy) at Tesco Lotus.
The Chon Buri venture is part of Tesco Lotus's mission to deliver a 50% reduction in CO2 emissions from all of its stores worldwide by 2020, and to bring that figure down to zero by the year 2050, Prasert explained, adding that calculations will be based on measurements taken at all Tesco supermarkets in 2006, the year that the company embarked on this initiative to reduce its global carbon footprint.
In addition to generating its own electricity, the Bang Phra branch was designed to save the maximum amount of energy, using a range of tactics. Optimum use has been made of natural light by constructing the roof from translucent tiles. Sunlight also enters through two rows of windows one located high up in the walls, the other between two sections of the roof . These split-level windows have been laminated with a UV filter which admits light but very little heat. A system has also been installed to monitor the level of lighting within the store and adjust this automatically via a battery of dimmer switches.
"This is the first site where we've installed a roof coated with UV protection; it lets in light but much less heat," Prasert explained, adding that a reflector located at the southern end of the store enables more natural light to penetrate the interior during daylight hours without inducing additional heat, this reducing the need for artificial lighting at no extra cost.
The Bang Phra branch also uses hydrocarbons in its refrigeration system since these release substantially less CO2 than once widely used refrigerants like hydrochlorofluorocarbons (HFCs) and chlorofluorocarbons (CFCs) which are now being phased out because of their ozone-depletion effects.
"We are also the first supermarket to use glass doors in our refrigerated display cases. This helps reduce energy loss while also keeping the interior cooler and the products fresher," Prasert said.
The standard lighting in other Tesco Lotus stores is provided by an energy-saving fluorescent tube called the T5, but since the Bang Phra branch was intended to be a model store it was decided to install LED lighting throughout. In addition to giving more brightness for less power, LED lighting is environmentally friendly as it does not emit UV rays, contains no harmful lead or mercury and lasts twice as long as conventional lighting, Prasert noted.
During daylight hours the store is usually able to meet all its energy needs from solar power. Banks of photovoltaic (PV) cells on the rooftop generate 66 kilowatts and the PV farm at the back of the store generates another 264kW on average. Since it is only necessary to tap into the mains electricity supply after dark, Prasert estimates that the store will be able to reduce the amount of power it takes from the national grid by 489,000 kilowatt-hour per year.
Several other methods have been used to reduce the need for electricity. And not all of them are high-tech. First, the walls of the store are not made of conventional bricks (or concrete blocks) and mortar. Instead, an ancient techniques called rammed earth has been utilised. Heavy clay, extracted from 10 metres below the surface, is compacted to give it what is termed a "high thermal mass". The resulting structure has better insulating properties and, according to Prasert, there is the added benefit that the procedure produces no chemical residues whatsoever.
Another energy-saving innovation is immediately noticeable when one enters the supermarket. For to do so one has to pass through two sets of motion sensor-controlled sliding doors. One set of doors is designed to close before the second set opens. This "double airlock" systems retains more cool air within the store, reducing the strain on the air-conditioning system and thus saving lots of energy.
The "smart" air-con system used in Si Racha is also cutting-edge. Called VRV (Variable Refrigerant Volume) air-conditioning, it keeps the temperature on the sales floor at a comfortable ambient level while using 15% less power than a conventional system. Instead of running all 24 of the store's air conditioner compressors simultaneously, temperature sensors throughout the building trigger automatic commands that activate or deactivate compressors, starting from a minimum of four machines. There is also a built-in voltage regulator that adjusts incoming voltage from the grid to the optimum level, thus reducing unnecessary power use and prolonging the life of air-con compressors and other equipment.
Another innovation is the use of porous concrete instead of tarmacadam to surface the outdoor car park. The pores in the concrete are designed to soak up and retain rainwater which, as it evaporates, cools the concrete and reduces the amount of heat that spreads to the supermarket building itself.
The store also has a rainwater-storage facility and this is put to good use in the watering of trees and other decorative plants in the compound, for washing cars and flushing toilets.
The Bang Phra branch was sited in the best position to capture sunlight for solar-power generation and the wind turbine selected is a model of local design which was found to be more suitable for use in Thailand. It can generate power from wind speeds of a mere four metres per second, making it more efficient than conventional high-speed turbines.
And it's not just the wind turbine out front that's been attracting attention. People in the local community have also been intrigued by the store's biogas system. Vegetables past their sell-by date and leftover bread from the in-house bakery are composted to produce natural gas which is then used in the store to cook food, thus saving on electricity and also providing a neat way of recycling organic waste material.
The no-emissions concept is still at quite an early stage, said Prasert, noting that more fine-tuning and calibration will probably be necessary. He described the project as a laboratory whose findings will help the company better the zero-carbon model in future stores.
But an experiment like this doesn't come cheap. Total investment in the Si Racha venture was in excess of 140 million baht, Prasert said, making it three times more expensive than a standard Tesco Lotus supermarket of the same size. He attributed this to the high cost of technology such as solar cells and LED lighting, for which the payback period could be more than a decade.
"But we'd like to think of this place as a learning centre," he said, "dispensing knowledge that anybody can benefit from."
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