Simple urban energy balance model for meso-scale simulations (SUMM)

We propose a new simple urban energy balance model for mesoscale simulations (SUMM). The SUMM consists of a 3-D theoretical radiation scheme and the conventional heat transfer expression that uses a network of resistances. The present model allows one to readily calculate the energy balance and surface temperature at each face of the urban canopy (i.e., roof, floor, and four vertical walls) without time-consuming iterations.

Compared with the previous simple urban models, SUMM has the following features: (1) SUMM can be applied to 3-D regular and staggered building arrays. (2) Multi reflection of short and long wave radiations within building layers can be theoretically solved without time consuming iterations. (3) Relative values of Bulk Transfer Coefficient (BTC) of six constituent surfaces are referred to a BTC-database for various building geometries. The BTC database was based on scale model experiments and Large Eddy Simulation outputs. (4) Indoor temperature prediction involving glazing, natural ventilation, and energy consumption is possible.

The performance of SUMM was evaluated by comparison with outdoor scale model experiments. The simulated energy balance and surface temperatures agreed well with the values measured on a reduced-scale hardware model corresponding to the numerical model geometry.