Winter cities suffer from heavy snowfalls and cold winds and must perform costly and energy-consuming snow removal. Within these winter cities, an urban design approach that considers public space environments and energy saving is required. This paper developed the concepts of smart block designs that reduce negative impacts of snow and wind as well as the saving energy during winter for winter cities. The study focused on the high-density blocks in downtown Sapporo, Hokkaido Japan (Fig. 5). Three urban block models, existing type, high-rise congregated type and skyscraper integrated type, were assessed by using snow and wind simulations in wind tunnel (Fig. 3). Climatic impacts of snow and wind in the public spaces were analyzed in Chapter 6 (Fig. 7~9). Using the results of the snow simulations, the energy requirements for removing snow in the public spaces were estimated in Chapter 7-1 (Table4). Building energy consumptions during winter in each urban block model were calculated by ‘Program for Primary Energy Consumption in Buildings’ in Chapter 7-2 (Table10). Based on the results of Chapter 7-1 and 7-2, total energy consumptions during winter in the urban block models were analyzed (Table10).
The results of this study lead to five desirable urban block design concepts for high-rise and high-density building blocks in winter cities, and showed the relationship between block energy consumption and energy for removing snow as follows:
[Desirable urban block design concepts]:
1) Skyscraper integrated type and high-rise congregated type presented fewer snowdrifts on the public spaces than the existing type. They were controlled by the urban block designs such as the unification of the building external facades and the heights of buildings, reducing the wind turbulence, thereby causing the fewer snowdrifts.
2) Skyscraper integrated type and high-rise congregated type presented less snow cover on the public spaces and less snow removal energy consumptions than the existing type.
3) Skyscraper integrated type presented fewer snowdrifts on the public spaces than high-rise congregated type. Because the buildings was taller in skyscraper integrated type, stronger deflected winds produces larger areas without snowdrifts. In addition, the roof of the podium in the skyscraper integrated type could catch the snow and reduce the snow cover on the public spaces.
4) Skyscraper integrated type presented less snow cover on the public spaces and less snow removal energy consumptions than high-rise congregated type. The snow removal energy consumption in skyscraper integrated type was about twenty percent less than in high-rise congregated type.
5) In skyscraper integrated type and high-rise congregated type, the external facades were set back from Kita 3 jo street and the open-spaces were set along the sidewalks. The snowdrifts were formed on the open-spaces and the snowdrifts on the sidewalks could be reduced.
[Relationship between block energy consumption and energy for removing snow]
Energy consumptions of snow removal were equivalent to about ten percent of the total energy consumptions during winter. In addition, saving the energy consumed by buildings will increase the ratio of snow removal energy to total energy consumptions during winter. It is important to consider not only saving building energy consumption but also the snow removal energy consumption for the smart block planning in winter cities.
This study shows the relationship between urban block design and snow removal energy consumption and the importance of snow removal energy consumption in the total energy consumption during winter. Future related research will consider detailed urban design guidelines to decrease total energy consumptions during winter.