Building form

BIM (2011) refers to the tall and skinny building as a vertical form which can maximise PL. In addi- tion to that, compact buildings can help to support and accurate both ther-

mal comfort and cooling. This is what Ahsan (2009) points out: the compactness can minimise the surface area of the envelope which reduces heat gains. Figure 4:17 is an example of a compact building. Ahsan (2009) confirmed that natural ventilation can be achieved through using a build- ing form that can be opened and outward oriented. Martin Pool Architects Munich (2011) designed a passive house in the city centre of Munich which is called Seitzstrasse, as shown in Figure 4:18. They consider the building to be compact especially in the warm zone area. In the section it

is clear how they consider the passive ventilation to be provided vertically through a stack vent which Figure 4:15: Compact building (Ahsan, 2009).

is the through path in each storey. Also, the perspective shows the number of windows on the façade. The construction mass can influence optimum PLVT positively or negatively. The concrete centre (2010) referred to the role of low mass on effectiveness of rapid heat up or cooling. Based on this statement, this factor has been considered as one of the most essential factors of building form.

Building form is the second main stage in the PD process. This stage comes after the previous one, which is site investigation, orientation and landscape, is completed. There is no point of site investiga- tion, if the building form which has been selected is not optimum. There are various forms that can help to maximise PL and PV. The United States Department of Energy (2000) referred to the need to consider the orientation, which should face 30 degrees to the south to maximise PL and PV. This can- not be achieved sometimes because there are several restrictions which can be obstacles. For example if the street is facing the north. In this case, the designer should try several forms without being re- stricted to one concept. The suitable form is selected based on the outside conditions and inside condition, on the one hand. On the other hand, designers should keep in their minds the safety of the building through simplifying the design, because the simple form will be clear and easy to observe.

There are several building forms which can enhance PDF at the same time as being simple. The various functions are difficult to achieve as each shape can have some functions but lose others or does not optimise them. Sigg et al (2006) classified the various forms from PLVT perspectives, as presented in Figure 4:19. This classification can help the designer to consider the rest of the functions which cannot meet the selected form as well as to be accurate when selecting the form of the building. BIM (2011) point out the several form types which can be used when designing PBD for optimising PLVT. Some forms can help to provide a lot of surfaces which of course can increase the possibility of providing windows. This can help the designer to optimise PL. The forms could be long, linear build- ings, providing lots of wall surfaces that can be used for windows to improve PL and PV, and this can create interoperability between both functions.

The third example which includes the atrium in the core level achieves 100% of PL in each space. Baker and Koen (2002) identified some limitations that can help the building form to benefit from PL. The site is one of these limitations which can affect the building form. The topography of site, shape, size, legislation, planning code and sun obstructions are limitations which should be compliant for optimising PLVT. All of these limitations may have an important impact on the building shape to enable it to access the PL. Some approaches such as courtyards, atria, galleria, and light wells have been adopted into both older and modern buildings.

The volume of the building (geometry) and its surface are various and should be suitable to apply PDS (Prom et al, 1989). Prom et al (1989) said that the form should be suitable for thermal comfort, solar gain, and ventilation. The various shape types are summarised in Figure 4:20. Each type of ge- ometry can help to apply PDS but there are differences on the level of performance in terms of LVT. The suitable shape is not limited to the three

strategies but also could be in terms of the cli- mate and seasons. The classification is shown in Figure 4:20 based on cold, temperature, hot/dry and hot/humid.

Prom et al (1989) added that the building ge- ometry should be accurate in several levels, starting from the global, followed by the urban level, followed by the building level, and then

the system level. In terms of the building level this could be in the suitable shape of the horizontal plan and vertical plan. Also, the building shape could be affected by the wind trend. For this reason, the designer should select the suitable shape based on an accurate wind analysis, as shown in Figure 4:21. Public Technology Inc and US Green Building Council (1996) confirmed that the building shape should minimise wind tolerance. For this purpose, the designer should take into account selection of the suitable shape, and shape of the building for maximum exposure to winter sun and summer breez- es. Balasbaneh (2010) referred to using high mass to cool the space and that will be through using the building equivalent heat sink. Murray et al (May, 2009) referred to the use of high mass in traditional homes for promoting night ventilation.

Code End User factors References

AB1 Design compact building form for optimum heating and ventilation

BIM (2011), Ahsan (2009), Martin Pool Archi- tects Munich (2011)

AB2 Use low mass construction to allow rapid The concrete centre (2010)

Figure 4:19: The suitable shapes based on climate and wind (Prom et al, 1989)

Figure 4:18: The various shapes (Prom et al, 1989)

heat-up or cooling of structure

AB3 Shape the building to maximise exposure to winter sun and summer breezes

United States Department of Energy (2000), Sigg et al (2006), BIM (2011), Baker and Koen (2002), Prom et al (1989), Public Technology Inc. and US Green Building Council (1996) AB4 Use high mass construction with appropriate

insulation to promote night ventilation

Murray etal (May, 2009), Balasbaneh (2010)

Table 4-2: End user Factors passive design functionality: building form end user factors