Space cooling of nZEB

Abstract

The International Energy Agency (IEA) predicts that the final energy demand for cooling worldwide will increase from current 4 to 9 EJ per year by the year 2050. There are several reasons for increased energy demand. The contemporary architecture trend of “all-glass” architecture is a significant reason for the increased energy need for cooling of the buildings. An increase number of domestic appliances cause increased use of electricity and, therefore internal heat gains that must be removed by cooling systems. The EU population is getting older, and it is estimated that in the year 2030 almost one third of population in EU will be older that 65 years; elderly people are more vulnerable to heat stress. As a consequence, more cooling systems will be installed. During the last century, cities become larger and built with low albedo materials (low reflection of shortwave solar irradiation) with limited green areas. As a result, urban and street canyon heat islands are more intense. It has been calculated that in a mid-size city, an urban island could cause increase the need for cold for 10 kWh/m2 of building area per year. Climate change is another reason for the increased energy demand for the cooling of buildings. The United States Environment Protection Agency (EPA) predicts that in hot climate regions the demand for energy for cooling will increase due to global warming by 5–20%. Note An urban heat island is defined by the difference in the maximal daily outdoor air temperature in the built environment and surrounding countryside; a street canyon heat island is defined by the difference in maximal daily outdoor air temperature in the particular street canyon and in the city. In cities with more than one million inhabitants, the intensity of the urban heat island could be as high as 6–10 °C; the intensity of the street canyon heat island in tall streets without trees could be 1–3 °C in non-windy conditions.