THE MIT DESIGN ADVISOR – A FAST, SIMPLE TOOL FOR ENERGY EFFICIENT BUILDING DESIGN Bryan Urban and Leon Glicksman Massachusetts Institute of Technology, Cambridge, MA ABSTRACT We present a simplified software tool for architects to assist with early-stage design of energy efficient buildings. Energy consumption in the buildings sector accounts for 25 to 30 percent of global carbon dioxide emissions. Due to inherent complexity, building modeling tools are often deferred to the later stages of design. In later stages many decisions are already finalized and the opportunities for design improvement are limited, expensive, and harder to implement. By helping designers address efficiency and comfort in the first hours of the design process, significant energy savings can be realized more easily and at reduced cost. We provide an overview of the Design Advisor tool (http://designadvisor.mit.edu ) including the input parameters, results, and some important modeling information. INTRODUCTION The daily operation of commercial and residential buildings comprises roughly one-third of the world’s primary energy consumption; heating, cooling, and artificial lighting systems account for the largest portion. Because buildings are typically operated for many years, there is great potential for reducing global energy needs through improved building design. Many existing energy simulation tools for buildings are very sophisticated and promise a high level of accuracy. Popular tools such as Energy Plus and DOE-2 are quite effective at simulating final building designs and are typically used for demonstrating compliance with performance standards such as LEED. The tool we present is different in that we target the early-stages of the design process: a time when design details are often sparse and uncertain, simulation time is limited, and major decisions are not yet finalized. Most tools are overly complicated for this task and do not provide an easy way to compare the tradeoffs between design options. The aim of our project is to provide a fast, simple tool for architects and building designers to assist in the decision making process during the first hours of design. In this paper we outline the capabilities and limitations of the Design Advisor tool. First we discuss the input parameters and compare our interface with those of popular industry-standard programs. Next we present some example software outputs and show their utility for building design. Finally we summarize the major assumptions inherent in the model and present a basic overview of how the predictions are made. SIMULATION – USER INTERFACE If a design tool is to be useful to most architects, it must not require an extensive technical background or lengthy amounts of training. Existing software tools have largely been designed for engineers, resulting in simulation packages that require detailed floor-plan inputs, promise excessively high accuracy, and produce results in a non-graphical manner. Setup time for these programs can take hours or days. At the early stage such extreme accuracy and detail is unnecessary and in fact unrealistic. Instead we take a simpler approach: by restricting the input space to the most critical design parameters we can rapidly predict a design’s performance. Our primary objective is not an exact performance prediction of the final building design. What is important is that the user is able to identify which design factors have the highest impact on energy use and thermal comfort relative to the others. Although we restrict the detail in the inputs, the computational model is still quite sophisticated. Discussions of simulation technique will follow. Input Space Described below are the basic input options available to the user for describing a building configuration: Second National IBPSA-USA Conference Cambridge, MA August 2-4, 2006 - 270 -