A survey among relevant consultants and contractors shows the need for better knowledge and more systematic information in order to make decisions regarding the selection of system for energy supply of ZEBs (Zero Emission Buildings). The ZEB centre aims to develop a computerbased tool for this purpose that will include both a calculation tool and an information database. This assignment will be part of this development.

The main objective of this work is to evaluate the cost optimality of different energy systems for a ZEB using the European cost optimal methodology introduced in the context of the EPBD (Energy Performance of Buildings). Both modelling and evaluation of energy performance of the building and its energy systems and calculation of costs are part of this assignment.

Modelling of a typical new residential building will be performed using the dynamic simulation tool IDA-ICE; while the calculation of costs will be based on the data previously collected by the student during his project assignment and summer job. The choice of the type of building to model will be made in connection with the pilot projects of the ZEB centre.

This assignment is closely related to The Research Centre on Zero Emission Building at NTNU and SINTEF (FME ZEB) that has the vision to eliminate the greenhouse gas emissions caused by buildings. The main objective of FME ZEB is to develop competitive products and solutions for existing and new buildings that will lead to market penetration of buildings that have zero emissions of greenhouse gases related to their production, operation and demolition.

Abstract

During the uncontrolled consumption period the building sector has come to account one of the greatest proportions of greenhouse gas emissions and energy use in industrial countries. In this context, European countries have decided to address the environmental challenge by promoting the use of renewable energies and the implementation of low energy consumption requirements. For these reasons, zero emission buildings, which have a net zero annual energy demand, were regarded as a possible solution. And everything points to believe that they will continue to be crucial in a recent future. Consultants and contractors have shown the need towards a better understanding and knowledge regarding the selection of renewable energy supply solution for ZEBs. Accordingly, this Mater Thesis aims to explain how to use the new methodology for a cost-optimal selection of energy systems in early design phase analysis. It consists on a number of guidelines and Excel files that serve as templates for different calculations. The project is part of the development of a decision support method that automates the process of selecting the best system, in this particular case in office buildings. This early design phase study is not only focused on giving a cost-optimal alternative but also on performing a full analysis in terms of energy performance. It also shows the steps for both the energy systems dimension and the selection of office building parameters. A concept office building with four storeys is selected and modelled in connection with the Norwegian ZEB centre’s project report 8. Following the Norwegian NZEB definition, the simulation software IDA-ICE is used as a tool for modelling the building and simulating the energy demand. It analyses six different energy supply combinations which were selected between available renewable technologies in Norway. In comparison to the previous study applied in residential buildings, this project introduces the building’s cooling demand as a new feature of the analysis. Therefore, reversible heat pumps, free-cooling with the ground and chillers are also taken into account. Further, energy systems are economically compared by using global cost calculations, following the European Cost Optimal Methodology. Results are given in a graph where global costs and CO2 emissions produced by the energy balance of the building are shown in each axis. Finally the cost-optimal energy supply, the system with lower global costs, is selected like the most suitable option. In addition, the building energy performance is also discussed as an important parameter to be considered in the decision making process. At the end, the sensitivity analysis shows stable results with regard to changes in energy price development and PV area.

Abstract

Zero Energy Buildings (ZEBs) are considered as one of the key elements to meet the Energy Strategy of the European Union. This paper investigates cost-optimal solutions for the energy system design in a ZEB and the subsequent grid impact. We use a Mixed Integer Linear (MILP) optimisation model that simultaneously optimises the building’s energy system design and the hourly operation. As a ZEB have onsite energy generation to compensate for the energy consumption, it is both importing and exporting electricity. The hourly time resolution identifies the factors that influence this import/export situation, also known as the building’s grid impact. An extensive case study of a multi-family house in Germany is performed. The findings show that the energy system design and the grid impact greatly depend on the ZEB definition, the existing policy instruments and on the current energy market conditions. The results indicate that due to the feed-in-tariff for PV, the cost-optimal energy design is fossil fuelled CHP combined with a large PV capacity, which causes large grid impacts. Further, we find that heat pumps are not a cost-optimal choice, even with lower electricity prices or with increased renewables in the electric power system.

An office building of about 2000 m2 heated floor area is being designed for the Norwegian Defense Estates Agency (Forsvarsbygg). The building will be located at Haakonsvern, about 15 km from the centre of Bergen, Norway. The design aims at meeting the ZEB criterion of net zero energy balance for building operation during a year. The energy for operation of the plug loads (computers, printers, etc.) is not included in the balance.