Cost-optimal Sizing of Solar Thermal and Photovoltaic Systems for the Heating and Cooling Needs of a Nearly Zero-energy Building: Design Methodology and Model Description

This paper deals with the cost-optimal sizing of solar technologies for thermal and electrical needs of residential or tertiary nearly Zero-Energy buildings. The proposed design procedure is based on lifetime simulation of building loads and energy systems; therefore, according to proper cost-optimality considerations, it is possible to find the best sizing of both heat and electricity generators in the context of high-efficiency buildings (e.g. number of solar thermal and PV modules). The paper is divided in two parts. In this first part, we describe general features and principles of the methodology, together with the physical models of building-plant system. Building requirements of thermal and electrical energy are evaluated according to internal loads and external climate, while energy system operation is simulated by a full set of equations reproducing the coupled behavior of each piece of equipment. A preliminary application example referring to a nearly Zero-Energy Building is also illustrated: In the second part of the work, we will apply and discuss the overall simulation-based optimization procedure. Results show the notable benefits of the proposed design approach with respect to traditional ones, in terms of both energy and economic savings. Besides, the proposed methodology can be successfully applied in the more general framework of Net Zero Energy Buildings (NZEBs) in order to fulfill recent regulatory restrictions and objectives in building energy performances.