Progetto SIMEA - Automatica - Università degli Studi di Padova

SIMEA Stato dell’arte energetica degli edifici
1.2.41. SUNREL
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Doc.No 20100610.SIMEA.MR.03
Versione 1
SUNREL is an hourly building energy
simulation program developed by NREL's
Center for Building and Thermal Systems that
aids in the design of small energy-efficient
buildings where the loads are dominated by the dynamic interactions between the building's envelope, its
environment, and its occupants.
The program is based on fundamental models of physical behaviour and includes algorithms
specifically for passive technologies, such as Trombe walls, programmable window shading, advanced
glazing, natural ventilation, and rock bins. Conduction is calculated with a 1-D finite difference formulation;
therefore, there is no practical limit on the thickness of walls or thermal capacitance.
Interzone heat transfer by convection and radiation is handled by user defined heat transfer
coefficients. External surface convection coefficients are user defined (or default) constants. Interior surface
convection and radiation heat transfer is calculated using user defined (or default) constants. SUNREL has a
simplified multizone nodal airflow algorithm that can be used to calculate infiltration and natural ventilation.
Inputs for infiltration include the effective leakage area per zone and the estimated distribution of the
leakage area over each wall. The natural ventilation inputs include the opening size, height, location, and
operating temperature schedule. Wind pressure coefficients can be user defined or calculated from a simple
correlation using wind speed and direction. Windows can be modeled with detailed optical properties and Uvalues
or via data import from Window 4 or 5.
Thermochromic windows can also be modeled if the optical data is available to create a Window
model. SUNREL only models idealized HVAC equipment. The equipment and loads calculations are solved
simultaneously, and the equipment capacities can be fixed by the user or set to always meet the load. Fans
can be used to move a schedulable fixed amount of air between zones or from outside. SUNREL can read
TMY, TMY2, BLAST, and SUNREL weather files. A graphical interface can be used to create and revise
the text input files. The interface allows a single run or parametric runs for a single variable at a time.
1.2.41.1. Validation/Testing
SUNREL and SERI-RES have both been extensively tested as part of the IEA Solar Heating and
Cooling Programme�s efforts to validate building energy simulation software. The program will report if
stability or convergence criteria are not maintained, and energy balances can be observed from output reports
available to the user.
1.2.41.2. Expertise Required
Knowledge of mechanical engineering, building heat transfer.
1.2.41.3. Users
More than 100. Also the underlying engine for TREAT.
1.2.41.4. Audience
Engineers, energy consultants, scientists, designers.
1.2.41.5. Input
Thermophysical and optical properties of the building, simplified geometric description, and hourly
weather data.