Sensitivity analysis of building form and BIPVT energy performance for net-zero energy early-design stage consideration

Abstract

This study examines the influence of building form – comprised of plan shape and roof slope – on the net annual energy performance of solar net-zero energy (NZE) buildings. The renewable energy system used is the building-integrated photovoltaics with thermal heat recovery (BIPVT). BIPVT is a relatively new enhancement of the building-integrated photovoltaics (BIPV) system which others have studied for the effects of building form on building energy demand and energy generation. Previous sensitivity analyses of building form have typically not considered BIPV or BIPVT. When they have, it has been limited to simple, prismatic forms; it is unclear how more complex or compound building forms impact building energy demand and BIPVT generation. Therefore this study analyzes the relationship between building form and BIPVT performance to provide guidance for medium-sized NZE commercial and institutional building design at the early design stage. The main input parameters are the building form: compound or complex plan shapes, and BIPVT roof slope. Also included are: building orientation, window to wall ratio (WWR), and U-value. These parameters are evaluated in a heating dominated climate to determine the parameters sensitive to the net energy demand – the balance between annual energy loads including heating/cooling energy demand and PV electricity generation and useful thermal heat recovery. A customized BIPVT model is used in TRNSYS simulations. A variance-based ANOVA global sensitivity analysis method is used for both main and interaction effects. Results show that each of the form variations studied is able to reach NZE using different combinations of input values. The most sensitive input parameters for the NZE output target are the BIPVT roof tilt angle, the azimuth, WWR (South), plan shape, and WWR (North). Each one is quantified. This information may provide building designers guidance at the early design stage.