Sustainable design optimization of rural houses in north China .

摘要

With the rapid economic development of China, the living standards in rural areas have been experiencing improvement over the past two decades. One important aspect of the improved living standards is housing, which has been transformed from traditional adobe or stone structures into modern brick and concrete ones. In the meantime, active heating and cooling systems are gradually being incorporated and residents are requiring more comfortable indoor air temperatures during cold winters and hot summers. However, most rural houses have no insulation in their exterior walls and roofs. The question is whether or not it is economically viable to build houses with insulated exterior walls and roofs, and to what extent should they be insulated.;In order to answer these questions, the author has created one base hypothetical case and two evolutionary hypothetical cases. The base case is assumed to represent typical rural houses in the studied region of northern rural China, with its heating set point temperature at 13°C (55°F) and cooling set point temperature at 29°C (84°F). The two revolutionary hypothetical cases, reflecting the improving living standards in rural areas in the future, are the same with the base case, except that the set point temperatures are different. The heating set point temperature is 16°C (61°F) for evolutionary case 1 and 18°C (64°F) for evolutionary case 2. The cooling set point temperature is 26°C (79°F) for evolutionary case 1 and 23°C (73°F) for evolutionary case 2. The life cycle costs of each case with different insulation levels are calculated based on the initial cost and energy consumption data from EnergyPlus energy modeling software.;For all three cases, it was cost effective to insulate exterior walls and roofs. The optimal insulation scenario is 50 mm (2 inches) Expanded Polystyrene (EPS) wall and 25 mm (1 inch) Extruded Polystyrene (XPS) roof for the base case. The best insulation scenarios for evolutionary case 1 and case 2 is 100 mm (3.9 inches) EPS wall and 75 mm (3 inches) XPS roof and 100 mm (3.9 inches) EPS wall and 100 mm (3.9 inches) XPS roof respectively. It has also been found that the determinants on the optimal insulation scenarios are the heating and cooling set point temperatures, energy prices, lifetimes of houses and selected discount rates.