公益財団法人

セコム科学技術振興財団

研究成果報告書

研究課題名

流体数値シミュレーションによる個別住宅の屋根雪危険度判定
Assessment of Hazard caused by Roof Snow on Detached Houses
based on CFD Simulation Model
研究期間
平成 23 年 4 月 ～ 平成 24 年 10 月

報告年月
平成 24 年 10 月
研究代表者

東北大学大学院

工学研究科

都市・建築学専攻

教授

灯

持田

Professor, Dept. of Architecture & Building Science Graduate School of Engineering,Tohoku University
Akashi MochidaAbstract
In every winter, many casualties occur during work to remove roof snow in Japan. In order todecrease such accidents, it is important to preliminarily assess the degree of hazard associated withroof snow and take countermeasures such as making the roof shape simpler or choosing a proper
method of snow removal. However, it is very difficult to predict snow distribution on roofs of detachedhouses, because snow does not accumulate uniformly on their roofs. The snow distribution on theroofs is strongly dependent on the geometry of buildings, surrounding conditions, wind direction andother factors, and therefore the level of hazard due to roof snow cannot be properly determined only
by geometric configurations. The aims of this study are to develop a prediction system for the snow
distribution on roofs of detached houses with arbitrary geometries using CFD (Computational FluidDynamics) simulation with snowdrift model, also taking into account the influence of surrounding
buildings, and to validate the accuracy of the prediction system in terms of assessment of the hazard
caused by the roof snow.
Firstly, a prototype of the simulation model predicting roof snow distribution was developed. The
simulation model is based on the existing knowledge on wind and snowdrift simulations used in theresearch fields of architecture and civil engineering. In addition, for improving the accessibility ofend-users, a pre-processing system, which can easily handle terrain and building geometry data, anda post-processing system, which can comprehensibly visualizes the results of calculations, were also
developed.
Next, an accuracy of the developed model was verified by comparing with results of fieldmeasurements. In this study, roof snow distributions on actual detached houses were measured in
Sapporo City and Shimokawa Town for the validation data, in order to demonstrate the applicabilityof the prediction system to the climate conditions in Hokkaido. As a result of comparing thecalculated roof snow distribution with the measured one, good quantitative correspondence between
the results was observed. However, it can be pointed out that further investigations are necessary on
detailed observation of actual snowdrift phenomenon on the roofs and the modeling of snow cornicedevelopment, etc.
Finally, the prediction system developed in this study was evaluated by third-party authorities.
Interviews and questionnaire investigations were conducted to administrators of building division
for several local governments in Hokkaido, building engineers and architects worked in Shimokawa
Town and ordinary residents in the suburbs of Sapporo City. As a result, potential needs for theprediction system of the roof snow distribution for assessing roof snow hazard were confirmed. It wasalso confirmed that a required cost will be an important factor for practical use. Because a detachedhouse is privately purchased in the usual case, it is difficult to cover extra expenses in design stage.
Therefore, it is necessary to consider how to reduce the costs and establish a funding framework. In
addition, some issues to be more investigated were revealed, i.e., clarification of the role and rules ofthe prediction system during practical planning or design stage, consensus on cost for the values ofthe outcomes, etc.