The IEA Reference Scenario assumes that the efficiency of energy use - the amount of energy needed to provide a given amount of energy service - will continue to improve at a pace similar to that of the past three decades. Because most of the energy-using capital stock has a long life, technological advances can affect the average efficiency of equipment and appliances in use only very gradually. In stationary energy uses in the industrial, commercial and residential sectors, progressive improvements in energy efficiency are assumed to occur as a result of ongoing technological advances. For example, the growing deployment of integrated building designs, which incorporate efficient lighting, heating and cooling systems, will reduce energy consumption per square metre of office space in new office buildings. Energy efficiency standards and labelling programs already in place will continue to encourage more efficient equipment and appliances in these sectors. However, these efficiency improvements will be very gradual, because of the slow rate of replacement of energy-capital stock, especially buildings.