My idea for the project for Digital Urban -course was to continue with the theme I started in the the Urban Challenge Studio 1 -course: comparing different building efficiencies in a certain land area. In Esri’s City Engine, I was modifying the plot and building rules such as plot division, building height and setbacks to force the software produce four different type of block structures resulting in a similar efficiency (and floor area m2’s).
I ended up in two different type of closed blocks and two different type of blocks with separate buildings. Blocks with different structures differs in terms of building height, footprint area and how uniform or fragmented the footprint of the built area is. Four models and their key figures are presented in figure 1:
First two models A and B are presenting exactly the same shape of a closed block, but the street setback setting is varied. Street setback is the distance from building footprint to the street. It is often left unbuilt to serve for e.g. maintenance purposes such as snow removal, but most of the time it is unused – which raises the question do we really need them around every building? As the comparison of the key figures of A and B point out, the effect of the 3-meter setback is significant on the building efficiency (1.8 vs. 2.1). Same block without the street setback produces 1440 m2 (+13%) more total floor area, which equals for example to 28 apartments in size of 50 m2. The footprint of the block B is bigger than in A, but since it is utilizing the buffer zone outside the building, it enables also a bigger inner yard area for the inhabitants.
The surprising large effect of the buffer zone is due to the geometric principle, that size of an area isn’t growing linearly with the distance of its radius, but exponentially with the square of that distance. If the floor area of a single block varies this much depending on the setback rule, it is clear how large effect it can have in a neighborhood or city level. The importance of understanding the geometry and the effects of buffers for the efficient use of land area have been discussed e.g. by Unwin (1912) and Vaattovaara & Joutsiniemi (2016). One of the benefits of rule-based approach and softwares is the ability to apply this type of rules, and instantly evaluate the impacts to the whole model whether it is a single block, neighborhood or a complete city.
Despite the problem of parcel size in model C, key figures of the two blocks with separate buildings (C & D) points out, that to reach the same building efficiency than the closed blocks, the number of floors has to be higher. The unbuilt areas of a parcel in dot-type building block C are fragmented into several yards between the houses. In the lamel-type building block D two yards are connected and are forming a wider park-type of yard between the buildings. In comparison to the closed blocks, separate buildings and yards might provide easier administration for the housing condominiums, since they have their own buildings and yards to maintain.
In addition I did experiment with the City Engines sunlight settings. In figure 2 is presented the sunlight conditions of the four blocks in winter- and summertime:
The blocks are pointing towards north-west, since the geographic location in the City Engine model is along Vihdintie in Haaga. Left part presents the sunlight in the end of October at 12:00 and 15:00. Right part presents the sunlight in the middle of June at 12:00 and 18:00. The wintertime afternoon light conditions were captured earlier time of day because at 18:00 in October the sun is already gone down, and it would have demonstrated mainly the darkness without the shades.
Comparison of the closed blocks and separate building blocks reveal, that most of the separate buildings are getting more light in the wintertime than the buildings in the closed blocks. I didn’t pay attention towards placement and angles of buildings in order to optimize the sunlight, but as the dark wintertime pictures show, very little light is entering the inner yards. To enable sunlight to get into the buildings even a little in winter, it is important to take aspects of placement angles and building heights into account. Especially the closed blocks are difficult in terms of sunlight, and for example an entrance into the inner yard could be positioned in the southern end to increase the amount of light getting in to the block.
Unwin, R 1912. Nothing gained by overcrowding!, P.S. Jung & Son, Westminister.
Vaattovaara, M and Joutsiniemi, A 2016. Vääristynyttä tiiviyttä uusia tutkimuskysymyksiä. Terra 128: 1/2016.