Planting a green garden on the roof of a building can help increase its energy performance; the vegetation infrastructure of soil, insulating and waterproof material and the vegetation itself, form an effective insulation layer on the roof of the building. Considering that the roof constitutes the primary source of energy waste in a building it is evident that planting a garden on the roof will effectively reduce unwanted energy gains from radiation in summer and reduce internal heat losses in winter – see green buildings: Rational solutions.