Environmental Engineering Reference
In-Depth Information
the minimal quantity of energy. CE is the financial expenditure on energy
relative to the level of environmental comfort and productivity that the
building occupants attained. The overall CE can be increased by improving
the IEQ and the EE of a building [67].
Urban planning has a considerable impact on the future EE of buildings,
and planners lack useful tools to support their decisions. A study was made
presenting a new method based on a genetic algorithm that is able to search
for optimum urban forms in mid-latitude climates (35-50°). Here, more
energy-efficient urban forms are defined as those that have high building
absorptance in winter and low summer building absorptance. These forms
can be designed by choosing among regular tridimensional building geome-
tries with fixed floor space indices, which can be parameterised by adjusting
the following variables: number of floors, building length ratio, grid azimuth
and aspect ratio on both directions. The results obtained show that adequate
urban planning, based on the consideration of the local radiation conditions
as a function of latitude, may result in significantly better building thermal
performance. In particular, it is concluded that the highest latitudes are more
restrictive in terms of optimal solutions: pavilions (cross-sectional square
blocks) are the best solutions for latitudes of 50° and terraces (blocks infinite
in length) are preferred for 45°. For lower latitudes, all urban forms are pos-
sible. In terms of grid angle with the cardinal direction, it is concluded that
the angle should stay between −15° and +15°, except for the latitude of 50°
where it can ranges from −45° to +45°. For slab and terrace urban forms, the
spacing between blocks in the north-south direction should be maximised,
quantified by a building-height-to-street-width (aspect) ratio that decreases
with the increase of latitude, ranging from 0.6 for a latitude of 35°, to 0.4 for
a latitude of 45°. For pavilions, the north-south aspect ratio is independent
of latitude and should stay close to 0.7. The pavilion is the urban form that
allows for a larger number of floors [78].
Arguably, the most successful designs were in fact the simplest. Paying
attention to orientation, plan and form can have far greater impact on energy
performance than opting for elaborate solutions. However, a design strategy
can fail when those responsible for specifying materials, for example, do not
implement the passive solar strategy correctly. Similarly, cost-cutting exer-
cises can seriously upset the effectiveness of a design strategy. Therefore, it is
imperative that a designer fully informs key personnel, such as the quantity
surveyor and client, about their design and be prepared to defend it. Therefore,
the designer should have an adequate understanding of how the occupants or
processes, such as ventilation, would function within the building. Thinking
through such processes in isolation without reference to others can lead to
conflicting strategies, which can have a detrimental impact upon perfor-
mance. Likewise, if the design intent of the building is not communicated to
its occupants, there is a risk that they will use it inappropriately, thus compro-
mising its performance. Hence, the designer should communicate in simple
terms the actions expected of the occupant to control the building [67].
