This research concerns the economics of energy-efficient buildings: by merging auction theory and hedonic regression analyses, the price premium paid in the Netherlands for energy-efficient office buildings is investigated. The importance of the transition to an energy-efficient built environment is underlined by the increasing Dutch and European regulations regarding energy efficiency within the real estate market. As a result, the market for energy-efficient buildings has grown considerably in recent years. Therefore, office buildings increasingly have various voluntary and mandatory energy certificates. Since 2008, the energy label has been the measure of the energy performance of a building in the Netherlands and is therefore included as a test unit in this study.Problem analysis Most studies in this field have been conducted in the United States, primarily because CoStar has an extensive database of commercial real estate. As the Netherlands does not have such a centrally organized database, research into this subject is made more complex. Over the last couple of years, there has been growing interest in the financial performance of energy efficient buildings. However, the relatively large deviation and sometimes improbable contradictions of the identified price premiums in the various hedonic price studies might indicate that in some cases the models suffer from misspecification. It is possible that this results in an over- or underestimation of the rental price premium of energy efficiency in the Netherlands. This research presents a refined model to better isolate the effect of energy efficiency on the willingness-to-pay from the overall building quality, and therewith to determine the realistic rental premium for energy efficiency in the Dutch office market. Aim of the study This study aimed to determine the rental premium for energy efficient office buildings at the level of an office unit in the Randstad. An office unit is the office space that is included in a lease contract. In addition to the economic factors, location, and building characteristics, it was particularly important to include building and facade aesthetic features in the analysis, because such a control was missing in most comparable studies. It was expected that by controlling for aesthetic building and facade features, the rental premium for energy-efficient office buildings would be lower because the effect of energy efficiency on the rental price would be better isolated. Relevance Previous research in this field has shown that tenants are prepared to pay for energy-efficient office buildings. However, that research rarely controls for aesthetic building and facade features, which VII creates a gap in academic knowledge. By operationalizing and quantifying building and facade features, it is possible to control for these features. Therefore, the added academic value of this research is the more in-depth control of the aesthetic building and facade features. This research into the rental premium of energy-efficient office buildings in the Randstad contributes to the knowledge of stakeholders such as investors, developers, researchers, real estate agents, urban planners and policymakers. They need insight in the dynamics and influence of the energy efficiency of office buildings on the various office markets. This research offers the possibility of a practical application for the price characteristic as a benchmark within the valuation process. Methodology The aim of this research is to determine the rental premium of energy-efficient office buildings. The research wanted to give an accurate description of the actions that must be taken to achieve the goal of the research (Figure 2). Step 1 describes the reason and defines the problem statement by analysing the current context of the research field. Step 2 relates to the theoretical basis for regression analysis. Significant rental determinants within previous research have been identified to create a theoretical basis for the regression model. In step 3, data is collected for the multiple regression analysis and the mathematical specifications of the model are formulated. In step 4, the collected data is analysed and the regression model is formulated and designed. Different models are constructed and investigated. Step 5 concerns the interpretation of the model results. The re-evaluation and improvement of the content in an earlier phase resulted in an integrated design process in which the definitive regression model of this research was constructed. Results and conclusions The Research shows a positive rental premium for energy-efficient office buildings. The estimates of the predictive model indicate a rent price premium of 8.4% for energy efficient office buildings (label A-C) versus energy inefficient office buildings (label D-G). The research has also shown that different rental premiums are paid for different energy labels. The regression shows that when controlling for all other variables related to the macro, meso and micro levels, tenants are willing to pay substantially higher rents for office buildings with a B and or C label than for buildings with energy label A. Furthermore, tenants pay substantially lower rents for buildings with energy label E than for those with label A. No substantial differences have been demonstrated in the rent for the other energy labels. Perhaps, the lack of significance for buildings with a D, F or G label is the result of the small samples size in this research, so significant results are more difficult to achieve. In addition to the usual control of economic, location and building factors in rental premium research, this research has added a control level of building and facade aesthetic features. This control was missing in almost all comparable studies. If the control for aesthetic building and facade features is left out of consideration, the rental premium for energy-efficient office building would have been 13.5%, about 5% higher than the proven rent price premium of 8.4%. The addition of the level of control with regard to aesthetic building and facades features therefore has a significant effect on the rental price premium. This result was expected. The effect of energy efficiency on the rental price of office buildings is positive, but this is weaker than in previous studies because the effect of energy efficiency is better isolated through the extensive control of aesthetic building and facade features and was therefore determined more precisely.