Examination of life cycle cost in nZEB design

Abstract

In this paper, the feasibility and net present value of life cycle cost (LCC(NPV)) of nZEB under the meteorological conditions of Sapporo, Japan was examined for the model building. The procedure for examining the feasibility of nZEB is as follows. First, a building with envelope and equipment that meets the performance standards of the Japanese Building Energy Conservation Law is set as a reference building. Then the energy performance improvement measures of strengthening the thermal insulation performance, installing energy-saving lighting equipment, improving the efficiency of the heat source, installing the total heat exchanger, a combined heat and power and PV power generation were applied in order of cost effectiveness. And the change in LCC(NPV) was calculated. When all measures except PV power generation and ground source heat pump were adopted, the primary energy consumption was reduced by about 53%, which reached the level of ZEB Ready in Japan's ZEB evaluation. Furthermore, the installation of PV power generation reduced the primary energy consumption to about 25%. This is a nearly ZEB in Japan's ZEB evaluation. The point of becoming the cost optimum (minimum LCC(NPV)) was the level at which the primary energy consumption was about 50%. From this result, it was possible to show the importance of deciding the policy of ZEB while considering energy consumption and LCC(NPV) at the same time.