Environmentally progressive building practice is currently described using a variety of different tags: “green design”, “ecological design” or “sustainable design”. Although discussions regarding the most appropriate terminology describing environmentally progressive buildings can be deteriorated to meaningless semantics, the distinction between the notions of “green” and “sustainable” is critical in structuring environmental assessment methods [3]. These fundamental differences, surprisingly, often are neglected in existing rating systems. In original rating systems such as BREEAM (UK) or LEED (USA), these differences were quite well defined. In later generations of ratings systems (i.e., the systems that have been developed based on one or several original ones), the line between “green” and “sustainable” gradually faded away.

Assessing “building sustainability” performance, which is largely an issue of energy and mass flows, must be described in quantitative terms. On the other hand, the wider range of performance issues necessary within an assessment of “green” currently cannot avoid using more qualitative metrics to evaluate a building comprehensively [3]. A good combination of quantitative and qualitative criteria will ensure a thorough and sufficient evaluation. In contrast, any confusion will lead to inadequate structure of assessment criteria as a result of the ineffectiveness of the assessment.

This common confusion causes troubles for both the system’s developer (when building up assessment criteria) and users (when choosing among versions and using them to evaluate their buildings). For instance, although conceived as assessment tools to evaluate a completed building design, some existing rating systems such as BREEAM (UK), LEED (USA), GBTool (International), CASBEE, HK-BEAM (Hong Kong), etc. are commonly used as design tools. Whether or not a single system can function equally effectively as an assessment and as a design tool, is an important question. If the answer is “yes”, then what would be necessary in an assessment tool to enable it to be useful in design? The answer lies in the structure of the assessment framework and with the skill and enterprise of the users [4].

Tall-buildings have very distinctive technical and architectural features in comparison to other types of building. Low and medium-rise buildings, whether residential, commercial centers, schools or offices, all have similar construction, operation and demolition procedures. Tall-buildings, on the other hand, have totally different procedures and there is a need for specialized assessment criteria to be adequately evaluated. Existing rating systems which are commonly used to assess tall-buildings, such as BREEAM Office, CASBEE New Construction, GREEN STAR Office Design or HK-BEAM New Buildings, seriously lack dedicated assessment criteria for tall-buildings. Specifically, in the following areas: Construction technologies and procedures, foundation construction, building services, social and economic aspects, material utilization, energy utilization, earthquake management, living quality inside tall-buildings, etc. [2].

The systems of assessment criteria of existing tools such as BREEAM, LEED, CASBEE, GREEN STAR, etc. are often very rich in technical contents. Normally an individual architect cannot even finish the assessment process on his own because of lacking specialized technical knowledge. It often takes several days or even several weeks to finish an assessment (data collection, data input, document gathering, etc.) [2]. This then becomes a major issue in the design stage, where these tools are likely to be used again and again to test different design solutions.

The visions for TPSI rating scheme encompass the following main points:

TPSI is strictly a “Design” tool. Its interface, assessment method, result presentation and other features are dedicated to improving sustainable performance at the early stages of projects.

TPSI is specialized for high-rise buildings only (i.e., buildings of more than 20 stories). This means TPSI has a unique and dedicated system of assessment criteria and assessment methods, which increases the accuracy of the evaluations over other rating schemes.

TPSI is designed to be a user friendly, concise and handy tool. Assessment criteria are simplified and presented in an easy-to-understand way. The data inputting process will be speeded up. Technical inputs that are difficult to retrieve will be limited. TPSI is able to produce quick and sufficient evaluations, which makes it most suitable at the design stage when comparing different design schemes.

TPSI’s assessment criteria system is a harmony of Quantitative and Qualitative criteria.

Assessment results are presented in a well-defined and easy-to-communicate manner.

Results are in presented in the form of ratings, charts and graphs, enhancing the comparability of the outputs.

Setting a higher standard for sustainable tall-buildings/projects.

The TPSI system (2012 Version) comprises two components: The “Manual” (in the form of a booklet), and The “Calculator” (in the form of a Microsoft Excel tool). Users will claim “credits” for their tall building project by demonstrating compliance with the assessment criteria that are detailed in the “Manual”. The achieved credits will be inputted into the “Calculator” accordingly. The “Calculator” will then produce assessment results in form of ratings (percentage), charts, graphs, comments and recommendations on how to improve the design, etc.

TPSI contains 119 default issues divided into eight categories, covering all aspects of sustainable tall building development. These eight categories are further divided into two main groups. There is one additional category that allows users to earn extra credits for innovative features of their project or for exceeding the design standard stated in the “Manual”. A certain number of “credits” are available for each issue. Table 1 summarizes TPSI’s assessment criteria system and corresponding credits.

There are two main elements that can determine a Tall-building’s rating:

The Total Score; and

The Balance Factor (or TPSI Factor).

The “Calculator” incorporates all assessment mechanisms into an intricately coded Excel tool. All the users have to do is to put in the project’s information and claim the credits achieved. The Calculator will automatically calculate the Section Scores, apply the weighting, calculate the Total Score and TPSI Factor, produce graphs, charts, design recommendations, etc. TPSI Calculator is password-protected so users cannot change the core contents of the software; they can only input the project information and claim credits where awarded. TPSI Calculator 2012 Version contains 13 tabs in total (see Table 3).

The Trial Period, which commenced in October 2010, was divided into two main phases: the Self-testing Phase and the External-testing phase (or the Interview Process). During the Self-testing Phase, with the acknowledgement and support of Christopher Jones Studentship (University of Sheffield, School of Architecture), technical issues of TPSI were solved; and the first complete version of TPSI was ready to use. In the External-testing Phase, various aspects of TPSI were scrutinized and evaluated by multiple parties; and, based on the participants’ feedbacks, TPSI was continuously perfected.

TPSI was thoroughly reviewed during the Interview Process by a criteria system of nine categories (see Table 5). The Interview Process produced a reliable comparison between TPSI and other well-established existing rating systems (i.e., BREEAM, LEED, CASBEE, etc.) when being used in the case studies (tall-building projects).

Based on the opinions of the participants (Table 5), TPSI’s performance in the case studies was rated highest (85 points). This result is considered to be reliable considering the class and credibility of the interviewees as well as the number of case studies. The “Applicability” of TPSI was very well appreciated (scored 17/20 points compared to 15 points of both BREEAM and LEED), which proved the suitability and effectiveness of the assessment criteria system. Its “Methodology” point was also higher than that of BREEAM and LEED (12/15 compared to 11/15), which means the assessment process functioned smoothly. The design of TPSI Calculator earned it the highest score in the “Results Presentations” criterion (8/8). Most importantly, tall-building projects that utilized TPSI had improved their sustainability aspects more than all other rating systems, expressed by the “Performance Improvement” point of 11/12, compared to 9/12, 8/12 and 7/12 of BREEAM, LEED and CASBEE respectively.

The Interview Process also revealed TPSI’s drawbacks. While TPSI’s “Availability” can only be improved after it becomes available to general users, other features can be enhanced. The “Data Inputting” process, at the moment, is over scored by LEED (6/8 compared to 7/8). This has been foreseen as a limitation of the research, since the human resources are not enough to build up some of assessment mechanisms, resulting in the fact that users have to refer to external standards while working in several TPSI issues. Also, the standard level of TPSI was not rated higher than that of BREEAM and LEED although it was one of the initial goals. This feature has been improved by the modification of TPSI Issues’ requirements.

To conclude, the Trial Period indicated TPSI’s advantages and disadvantages when being used in reality, which in turn helped in perfecting the rating system. It has successfully confirmed TPSI’s values as well as the contributions of the research. Opportunities also arose during this period, which afforded further development of the research and extra validation of TPSI rating system.

In March 2011, the research received a £ 50,000 EPSRC (the Engineering and Physical Sciences Research Council of the UK) funding from the University of Sheffield’s Knowledge Transfer Account (KTA) to develop TPSI further into a commercial online rating tool. A KTA Proof of Concept project was established, which was named “TPSI Project”, and is now under development.

The core of the project is the development of TPSI into a Web-based Design/Rating Tool (under the new name—“GreenLight”). The online tool will allow users to:

Log in and register their high-rise projects;

Use the online system to assess the sustainability of their projects;

Use the online system as a design tool or a checklist to follow up and manage their projects throughout its’ stages;

View other rated projects, compare them with their own projects, learn from the others;

Communicate with other users;

The online tool would be a huge library of tall-building projects. The system would not simply be a rating tool anymore. It will collect all information about a project when it is registered (design, technical information, sustainable strategies, etc.) and make them valuable to other users.

The second stage is to develop a social-network for individuals and organizations that work in the Built Environment worldwide, named “Sustainable Network”. The network will create an online community, an all-in-one stop for anyone involved in the Built Environment. Users will have access to an open and interactive community filled with opportunities. The network will also be equipped with interactive design and management applications. A free Projects Library will also be opened to the public where users can get information about Sustainable Projects worldwide. Users themselves will help in developing this library.

TPSI and other third-party applications will be available on this network, making it the perfect platform to promote and publicize the TPSI rating scheme. This is what has been missing from other rating schemes, and what will make this project unique, apart from the tool itself. Figures 7–10 show some screenshots of the GreenLight online tool and the Sustainable Network. Both the tool and the network will be available at: http://www.sustainable-network.org.