WUFI

Hello.

This post is somewhat related to the former post on "explicit radiation balance".

In order to double check the overheat issue caused by incident solar radiation, we set up simple two zones projects.
Each zone has a geometry of 4m x 3m x 4m (W x H X D) and is connecting with each other by a partition wall paralleled to the exterior wall.
rest of walls are kind of inner walls exposed to the same boundary condition as the zone respectively.
The exterior wall has a single glazing window of 2m x 2m (W x H) .
Tokyo is specified for the exterior climate condition.
Please refer the figures on the project geometry.
Two project have ran, i.e., a case for South and North facade and the other for East and West facade.

In two projects, we assume no internal heat release nor heating and cooling energy supply so that the inner temperature profiles are the pure natural temperature composed by outer temperature, short and long wave radiations, etc for Tokyo.

[ to be continued]

[Results for South and North facade]

The temperature profiles for the south and north zones in the hottest day show similar variations with a small temperature offset.
The incident solar radiation profiles for the day are incredible since the northern solar radiation shows the similar peak and profile as the southern result. The direct term of the northern solar radiation in summer should have two peaks in the morning and the evening. However the diffused term might have a single peak in the solar noon, the combined total insolation for north should show somewhat different profile from the southern one.
[ to be continued ]

[results for East and West facades]
The temperature profiles for the east and west zones in the hottest day also show mystical profiles.
Since east zone seems to have a temperature peak in the morning, and west zone seems to show the peak in the late afternoon.
Because the incident solar radiations for the east and west zones are not well separated each other as in the following figure.
However two solar radiation profiles show different peaks, those are not split enough compare to our empirical knowledge.
I will send the project files via e-mail.
Please confirm the results and hope to get appropriate suggestions.

Best regards.

Hello,
as a first request, the temperature profiles displayed are for the hottest day (2015/07/25) following your description and not for the shown time scale below the relative humidity? If you change the displayed time for one graph, the displayed time is not automatically changed for the other graph and the time scale below.

I have tracked the simulation and put two screenshots for that day. The blue line is the diffuse radiation, the red line the direct solar radiation, computed for the south and north window. So this shows a very low direct radiation on that day. Following this I have investigated the solar radiation on the south and north window for the whole year. It seems that with the climate file for Tokyo, the direct solar radiation in summer is low on the south side, comparing the whole radiation averaged over 168h. The same I have observed for the East-West simulation. The direct solar radiation is pretty lower than the diffuse radiation (on both sides equal), leading to the not very separated overall radiation peak you have observed.

I have observed quite same results with another climate file (energy plus weather data) for Tokyo.

Regarding this you might can use measured climate data, or might have to adjust more realistic window parameters. The SHGC (solar heat gain coefficient) hemispherical is used to calculate the solar gain across the window depending on the diffuse radiation, the average, or incident angle depend SHGC is used for the direct solar radiation.

mpazold wrote:Hello,
as a first request, the temperature profiles displayed are for the hottest day (2015/07/25) following your description and not for the shown time scale below the relative humidity? If you change the displayed time for one graph, the displayed time is not automatically changed for the other graph and the time scale below.

I have tracked the simulation and put two screenshots for that day. The blue line is the diffuse radiation, the red line the direct solar radiation, computed for the south and north window. So this shows a very low direct radiation on that day.

solar radiation window south 25_07.PNG

solar radiation window north 25_07.PNG

Following this I have investigated the solar radiation on the south and north window for the whole year. It seems that with the climate file for Tokyo, the direct solar radiation in summer is low on the south side, comparing the whole radiation averaged over 168h.

solar radiation window south year 168h average.PNG

solar radiation window north year 168h average.PNG

The same I have observed for the East-West simulation. The direct solar radiation is pretty lower than the diffuse radiation (on both sides equal), leading to the not very separated overall radiation peak you have observed.

I have observed quite same results with another climate file (energy plus weather data) for Tokyo.

Regarding this you might can use measured climate data, or might have to adjust more realistic window parameters. The SHGC (solar heat gain coefficient) hemispherical is used to calculate the solar gain across the window depending on the diffuse radiation, the average, or incident angle depend SHGC is used for the direct solar radiation.

As you pointed out, the horizontal axis denotes 24 hours of the hottest day (2015/07/25) in the temperature profile figure.

It seems to be quite incredible solar radiation data even in the hottest summer day.
In the summer clear day, the direct normal solar radiation should have similar or the greater order than the horizontal diffused solar radiation.
In order to ask the adequateness of the separation scheme for the direct normal and horizontal diffused solar radiations introduced in the Extended AmeDas standard weather data for cities in Japan, it would be highly appreciated if you send me the figures on the summer profiles ( or degital hour by hour data for July, August and September) of the direct normal and horizontal diffused solar radiations for Tokyo so that I will ask the Japanese distributer to double check the solar radiation data.
Otherwise It would be highly appreciated if you could directly ask the developer Prof. Akasaka for the adequateness of the separated solar radiation of Tokyo.

Since this issue affects whole WUFI family software simulations under wether conditions in Japan, it is too serious to utilize WUFIs in Japan.

Thank you in advance for your continuous support.