Ben Avraham Oren
M.Sc. Thesis, 2012
Through this research a tool for the analysis and determination of the Green Potential (GP) of existing buildings was developed. The tool, derived from the Israel Green Buildings Standard SI 5281, allows the quick evaluation of a single building or the comparison of different buildings in order to understand their potential, both by designers before their intervention or by planning authorities as ways of determining development plans. The development and logic of the tool is be demonstrated through the analysis and comparisons of various iconic buildings in Israel, from the 1950-60’s and contemporaries.
The Israeli Green Buildings Standard SI 5281, is a system of criteria and requirements that define the framework for testing new buildings and buildings that passed a massive renovation. The green accreditation is based on a checklist and accumulation of credits to stand on a certain condition threshold.
However, it is also possible seeing the Green Standards as a comparative instrument for the analysis of the performance of existing buildings, regarding the subjects treated by the standard. Through the analysis and classification of these subjects according to the degree of building flexibility and intervention required for implementing each of its sections, tools for the determination of the Green Potential of existing buildings can be derived from current standards. The importance of reusing existing structures, on account of both environmental and economic considerations, was the motivation to deliver such a tool.
The potential of the GP tool
A tool for determination of the Green Potential of existing buildings can be used in varied ways. Besides of indicating the potential of a certain building to get certified by a green standard after being renovated, it can be implemented to investigate the extent of environmental issues assimilation in a specific project plans and to draw up a comparison between groups of buildings. If tool’s output is derived easily and quickly, it could even be used to structure new regional databases, appear as maps, indicating the Green Potential level of a certain city area. A quite simple way to provide accessibility to these new databases is to include the Green Potential maps in geographic information systems, as one of the information layers to consider – an effective mean for determine a planning strategy.
In order to obtain these potential applications of the suggested tool, it was characterized by several properties and qualities: (1) Credibility, that will enable comparison between different investigated buildings; (2) creating it as an easy to use and quick to apply tool, to guarantee a comprehensive future usage of it; (3) designing it as a progressive tool, that encourages entrepreneurs to take actions in order to improve buildings environmental performance; (4) suitability to future transformations and developments of the Green Buildings Standards, as a result of technological and cultural changes; (5) and finally, clear visual presentation of the examinations output data as a whole, yet can be dismantled into detailed information about every one of the Green Standard section’s results.
Facing the challenge of interpreting the Green Buildings Standard into a tool for evaluating the GP of existing buildings, as a first attempt the subjects treated by the standard was classified according to the degree of building flexibility and intervention required for implementing each of the standard sections. Consequently, the standard sections were divided into three groups of characteristics:
(1) Flexible Characteristics were defined as qualities that can be affected by renovation actions. A good example for Flexible Characteristic is addition of thermal insulation, which clearly can be improved during the course of renovation.
(2) Inflexible Characteristics were defined as qualities that can’t be affected by any act of renovation, but are expected to have future implication on the building environmental performance. The original structure shape and main orientation, for instance, are characteristics that may have a major implication on the building energy consumption, but can’t be affected by renovation.
(3) Finally the Design Phase Characteristics were defined as qualities that were determined by the original building design, they can’t be affected during any kind of renovation and may not have any future implication on the building performance. Thus we called them Indifferent Characteristics. For example, “minimization of damage to habitats”, one of the standard sections, is a characteristic that was determined by the design of the original building. Whether damage was done, renovation couldn’t make a difference. However, if the proposed renovation includes the construction of new building or sections, these characteristics must be also considered.
Using the method developed in this work, while a certain building is evaluated, the score of every interpreted section of the Green Buildings Standard can be marked differently, indicating the degree of building flexibility and its ability to win a specific section’s score.
The GP visual trace, composed by the evaluation process
According to the aspiration to create a clear visual presentation of the examination output data, a rectangular container for the total 100 credit points of the tool was drawn, given to an examined building. The 100 points, based on the maximum score of the Green Buildings Standard, are represented as the 100 cells of this container. During the evaluation process the colorful points are expected to fill out the container and paint it into a visual easily-comparable map. The container is marked by two lines that represent the threshold score of the standard for Green Building (55 points) and for Excellent Green Building (75 points).
The evaluation process, reflected in the creation course of the visual trace, is conducted by a sequence of questions:
(1) Can the building win extra points of the original design phase points? (2) what inflexible points does it obtain as is, before renovation? (3) what flexible points does it obtain as is? (4) and finally, what are the flexibility levels of the remaining points?
These questions are answered by evaluating the building according to the specific relevant GP tool sections, that were derived from the Green Buildings Standard. As the evaluation process ends, the 100 cell container meant to be filled. The result is a visual colorful map, a representation of the Green Potential of an examined building as a whole.
The analyzed buildings
The GP tool was developed through a comparative analysis of the performance of various iconic buildings in the city of Tel-Aviv, dwellings as well as office buildings, from the 1950-60’s and contemporaries. Our interest in these two eras, among other things, was aroused by the fact that buildings from the 1950-60’s were designed just before air conditioners got into use comprehensively, and seems to exhibit environmental awareness inherently. Conversely, contemporary constructions offer the technical possibilities to reach very good comfort through mechanical heating, cooling and other kinds of air conditioning, and therefore, in some cases, tend to forget the old knowledge about how to adapt buildings to the climate passively, and rely almost exclusively on mechanical engineers.
The GP tool allowed us to compare pairs of similar buildings with a certain difference we were interested in. The comparisons main goal was to draw conclusions about the influence of certain building quality on its Green Potential.
Trying to draw wider conclusions out of the buildings examinations, we looked for a method that will allow crosswise comparison. Therefore we stretched out the buildings visual traces into stripes, that present the potential 100 points as a sequence. That kind of presentation enabled as to arrange the data according to a different criteria at a time. For example, according to the building age, according to their GP, and so on.
As we put all of the stretched visual traces together, we found that the credit for 15 of the Green Standard’s sections was identical for all of the analyzed buildings. These sections were scored repeatedly by 32 points of the third defined flexibility levels and 12 of the fourth level. Excluding these sections, and their score, out of the examination can, on the one hand, shorten the process significantly and, on the other hand, to emphasize the differences between the buildings.
Some difficulties through the process of interpreting the standard strengthened our perception, that criterions of assessment tools such as the Green Standard and the GP suggested tool, should be clearly measurable and put accurately.
It appears that the energy section of the standard is an effective block for building that shows poor performance in that area to win a green classification.
Though only a small number of buildings were examined, there is a trend that can be noticed. As we thought, older structures from the 1950-60’s performed better than contemporary buildings. Nevertheless, sometimes it seemed that architects with deep environmental awareness, do not act accurately. This fact emphasize the need of measurable and precise criteria, as suggested here.
The GP tool can be used widely in order to enable comparison between structures and groups of buildings. Digitalizing the GP tool will open the opportunity to use the produced data as part of geographic information systems, and make it accessible for the planning authorities, planners, architects and entrepreneurs.