March 2002 • NREL/BK-550-30193 SUNREL™ Technical Reference Manual Prepared by Michael Deru, Ron Judkoff, and Paul Torcellini National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 NREL is a U.S. Department of Energy Laboratory Operated by Midwest Research Institute ••• Battelle ••• Bechtel Contract No. DE-AC36-99-GO10337 March 2002 • NREL/BK-550-30193 SUNREL™ Technical Reference Manual Prepared by Michael Deru, Ron Judkoff, and Paul Torcellini Prepared under Task No. BE90.6001 National Renewable Energy Laboratory 1617 Cole Boulevard Golden, Colorado 80401-3393 NREL is a U.S. Department of Energy Laboratory Operated by Midwest Research Institute ••• Battelle ••• Bechtel Contract No. DE-AC36-99-GO10337 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States government or any agency thereof. Available electronically at http://www.osti.gov/bridge Available for a processing fee to U.S. Department of Energy and its contractors, in paper, from: U.S. Department of Energy Office of Scientific and Technical Information P.O. Box 62 Oak Ridge, TN 37831-0062 phone: 865.576.8401 fax: 865.576.5728 email: [email protected] Available for sale to the public, in paper, from: U.S. Department of Commerce National Technical Information Service 5285 Port Royal Road Springfield, VA 22161 phone: 800.553.6847 fax: 703.605.6900 email: [email protected] online ordering: http://www.ntis.gov/ordering.htm Printed on paper containing at least 50% wastepaper, including 20% postconsumer waste FOREWORD Foreword In the past 30 years, numerous building energy simulation programs have been developed. Most have been dropped and forgotten because of poor physical models, lack of funding, lack of interest, and probably many other reasons. SUNREL is an upgrade of one of these programs, SERI-RES, which was released in the early 1980s. SERI-RES is an hourly calculation program based on fundamental models of physical behavior, but it needed to be upgraded to take advantage of the newer computing power of personal computers. SUNREL is the same basic program with some new models and a simple graphical interface. Along the way, a few bugs were also found and corrected. The original program was created to model small buildings with loads driven by the envelope. Some algorithms are specifically for passive technologies, such as Trombe walls and programmable window shading. SUNREL has added new features to make this a stronger program like models for advanced glazings and natural ventilation. The program has been used by researchers around the world and been proven to be accurate and reliable. Many people were involved with the creation of the original version of this program, when it was called SERI-RES. The major contributors were Larry Palmiter, Terry Wheeling, David Simms, David Wortman, Bob O'Doherty, and Ron Judkoff. SUNREL TABLE OF CONTENTS Table of Contents 1. Introduction..................................................................................................... 1 1.1 Description............................................................................................... 1 1.2 Limitations of the Program ....................................................................... 1 1.3 Organization of the Code......................................................................... 2 1.4 Running the Program............................................................................... 3 2. Thermal Modeling of Buildings ....................................................................... 5 2.1 General.................................................................................................... 5 2.2 The Building Description.......................................................................... 5 2.3 Runs ...................................................................................................... 8 2.4 Zones .................................................................................................... 10 2.5 Conduction............................................................................................. 11 2.6 Solar Gains ............................................................................................ 15 2.7 Equipment.............................................................................................. 21 2.8 Schedules.............................................................................................. 27 2.9 Output.................................................................................................... 28 3. Building Description Input File ...................................................................... 29 3.1 General.................................................................................................. 29 3.2 Description of Namelist Input ................................................................. 29 4. Technical Algorithms .................................................................................... 47 4.1 Introduction ............................................................................................ 47 4.2 Solar Algorithms .................................................................................... 50 4.3 Temperature Algorithms ........................................................................ 60 4.4 Equipment Algorithms............................................................................ 86 4.5 Latent Load Algorithms........................................................................ 100 5. References.................................................................................................. 105 Appendix A: SUNREL Output ........................................................................A-1 Appendix B: Weather File Formats ................................................................B-1 Appendix C: Using Window-4.1 with SUNREL.............................................. C-1 Appendix D: Sample Building Description Input File ..................................... D-1 SUNREL List of Figures Fig. 2-1. Thermal model of a simple building................................................... 6 Fig. 2-2. Layers available for making walls...................................................... 12 Fig. 2-3. Levels of detail for modeling a wood frame wall................................ 14 Fig. 2-4. Window size and location on an exterior surface .............................. 16 Fig. 2-5. Overhang and sidefin dimensions relative to an exterior surface...... 18 Fig. 2-6. Illustration of exterior distribution of solar radiation ........................... 19 Fig. 2-7. Illustration of interior distribution of solar radiation ............................ 21 Fig. 2-8. Illegal placement of fans ................................................................... 26 Fig. 2-9. Examples of allowable fans and rockbin placements........................ 27 Fig. 4-1. Pseudo-code fragment of the hourly calculations.............................. 48 Fig. 4-2. Angles for calculating the directional cosines of a vector from the surface to the sun........................................................................ 56 Fig. 4-3. Overlapping surface and shadow polygons....................................... 57 Fig. 4-4. Stack pressure across a wall............................................................. 66 Fig. 4-5. Possible wall layer types and the node configurations...................... 71 List of Tables Table 2-1. List of Data Sections....................................................................... 7 Table 4-1. Coefficients for Calculation of Absorbed Solar Radiation, Aij.......... 59 Table 4-2. Terrain Classifications for Infiltration Calculations .......................... 67 Table 4-3. Local Shielding Coefficients Used by SUNREL.............................. 67 Table 4-4. Fan Energy Delivery Function Coefficients.................................... 99 INTRODUCTION 1. Introduction 1.1. Description SUNREL is a building energy simulation software for small, envelope- dominated buildings. It is an upgrade of SERIRES version 1.0, which was written under the guidance of the Solar Energy Research Institute (SERI, now the National Renewable Energy Laboratory [NREL]). SERIRES was originally written in FORTRAN 66 for main-frame computers. As personal computers became more powerful, various groups around the world converted SERIRES to this platform. SERIRES has been well tested through experimentation and practical use and is one of the benchmark programs for the International Energy Association testing procedure, BESTEST (Judkoff and Neymark 1995). The current version of SUNREL has also been tested satisfactorily using the BESTEST procedure (Deru 1997). The upgrade of SERIRES to SUNREL was completed by Colorado