Major energy costs for hotels include heating, light and power (HLP).

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Sky Greens venture is supported by the Singaporean government and has another advantage over other urban farms around the world: abundant natural heating and light.

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And last spring, the company redesigned the oven, replacing the traditional light bulb used for baking with an electric heating element, then switching the oven's door from the side to the front.

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This means sealing air leaks around windows and doors, properly insulating attics, replacing standard light bulbs with compact fluorescent lamps and giving your heating and cooling systems an annual checkup to ensure they're running properly.

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