Re: [EnergyPlus_Support] why blinds not reducing heat gain through window?

["'julie, julie futcher, futcher' julieannfutcher@xxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>]

there are many  different urban heat islands - the most commonly talked about effect is the nocturnal canopy layer urban heat island...(CLUHI), that is the ait temperature difference between a non-urban setting and a urban setting... you are right these nocturnal air temperature differences are found to be more intense in the down town area... where the buildings are usually taller, blocking the transport of stored heat to the cold night time sky. this is governed by the amount of visible that a point of the urban surface can see...this  parameter is called the Sky view factor (SVF)... Urban Geometry is the prime mechanism for the amount of heat that can escape the system....
At the same location the daytime air temperatures are often found to be lower. as a result of the same parameter URBAN GEOMERTY
the parameters you describe (1) and (3) are found to make a contribution, but these are not as significant as the role of urban geometry...
Whilst materials & thermal storage plays a role, it is the trapping of this outgoing radiation that is the main factor...
The UHI are a significant and miss understood phenomena.... unfortunately, energy+ other such tools are limited in their ability to report on these effects, which cannot be accounted for entirely with an air temperature uplift and the lowering of wind speeds... BUT this is something we are working on!
I think its worth running the thing again with the blinds open at night!
J



From: "Joe Huang YJHuang@xxxxxxxxxxxxxxxxxxxxxxxx [EnergyPlus_Support]" <EnergyPlus_Support@xxxxxxxxxxxxxxx>
To: EnergyPlus_Support@xxxxxxxxxxxxxxx
Sent: Friday, 10 October 2014, 20:30
Subject: Re: [EnergyPlus_Support] why blinds not reducing heat gain through window?


 I doubt very much that blocking heat loss to the night sky is the prime cause of the urban heat island.