Improving the Design of Energy-Efficient Building Retrofitting: Design Guidelines, Energy Simulations, and Selecting of Technologies

Introduction

The building should be considered as a composition, whose functionality is affected by its various elements. The functionality of the building is largely dependent on well-functioning structures that also form a framework for building service systems. In the retrofitting process, replacing a single part, e.g. a window, often affects other structures and systems, so its design must involve understanding the factors affecting the entire building performance. The starting point for planning, also for planning of retrofitting actions, should be the prospective end result in terms of a good indoor climate and energy efficiency. Solutions for retrofitting are always case-specific, and they also include cost-effectiveness analyses.

The primary goal of retrofitting is to repair damaged or obsolete parts but the activity can also aim at improving functionality in all aspects. Since the service life of the repaired structure corresponds to a new one after repair, the target level of the correction needs to be set accordingly (Ojanen et al. 2017). According to Ojanen, requirements may also be other than only regulatory requirements, such as clients' wish to have a higher quality indoor climate and lower energy consumption than before. High quality solutions typically reduce energy consumption and increase living comfort, but the success of the action requires that property is considered as a whole (Ojanen et al. 2017). In this contexts, clients must require the designer, contractor and supervisor to have good expertise on retrofitting. Actions for improving of energy efficiency are undertaken almost exclusively at the same time when some construction or technical systems are repaired or renewed, instead of separate activities.

Choices made during the design of the retrofitting will affect for decades, e.g. the energy demand of the building and other maintenance costs. Better energy efficiency extends the lifespan of the building, improves user comfort and can affect the building's value as a property. An appropriately repaired building consumes less energy, which reduces operating costs. Design is encouraged in the direction of introducing long-term passive measures for saving future heating and cooling energy. When designing a retrofitting project, the order of the design should proceed, as far as possible, toward the minimization of energy demand. This includes, among others, actions to reduce heat losses and the need for cooling, to enhance the efficiency of electricity usage, utilize free (passive) energy sources, control the energy demand, and ultimately select appropriate energy sources (potentially produced on-site).

This chapter presents how these design aims can be achieved by using up to date methodological know-how and the new software tools efficiently employing energy simulations. The chapter is structured as follows. Background describes the current use of energy simulations in retrofitting, and how BIM fosters the paradigm change in the building design processes. Then, the main focus of the chapter is described, followed by describing the design science research methodology. An overview of the developed DESIGN4ENERGY methodology is given for designing energy efficient buildings with holistic approach. Next, developed holistic design guidelines are presented, including to-do lists for designers for the retrofitting phase. These are followed by showing, how energy simulations can be utilised in retrofitting, and how to select the retrofitting options. Finally, future research directions are discussed and conclusions summarise the main findings of the presented research.