Measures to Promote Sustainability

Again, construction, which consumes and discards resources and energy in enormous quantities, is one field where we must act urgently to develop and promote techniques and policies able to assist the drive towards sustainability.

There has been a growing movement towards sustainable construction since the second half of the 1980s, leading to the development of various methods for evaluating the environmental performance of buildings. Methods developed overseas include BREEAM (Building Research Establishment Environmental Assessment Method) in the UK, LEED^TM (Leadership in Energy and Environment Design) in the USA, and GB Tool (Green Building Tool) as an international project. These methods have attracted interest around the world. This kind of assessment, with the publication of the results, is one of the best methods now available to provide an incentive for clients, owners, designers and users to develop and promote highly sustainable construction practices.

CASBEE was developed according to the following policies:

1) The system should be structured to award high assessments to superior buildings, thereby enhancing incentives to designers and others.
2) The assessment system should be as simple as possible.
3) The system should be applicable to buildings in a wide range of applications.
4) The system should take into consideration issues and problems peculiar to Japan and Asia.

Framework of CASBEE: CASBEE Family

Building Lifecycle and Four Assessment Tools

As shown in figure1, CASBEE was developed in the suite of architectural design process, starting from the pre-design stage and continuing through design and post design stages.

Figure.1 The cyclical process of building design

CASBEE is composed of four assessment tools corresponding to the building lifecycle. "CASBEE Family" is the collective name for these four tools and the expanded tools for specific purposes, which are listed below. The CASBEE assessment tools are CASBEE for Pre-design, CASBEE for New Construction, CASBEE for Existing Building and CASBEE for Renovation, to serve at each stage of the design process. Each tool is intended for a separate purpose and target user, and is designed to accommodate a wide range of uses (offices, schools, apartments, etc.) in the evaluated buildings.

Figure.2 Building Lifecycle and Four Assessment Tools
(please click the above image for enlarging.)

Names of the four basic tools

CASBEE for Pre-design (underdevelopment)
This tool aims to assist the owner, planner and others involved at the planning (pre-design) stage of the project. It has two main roles:
1) To assist in grasping issues such as the basic environmental impact of the project and selecting a suitable site.
2) To evaluate the environmental performance of the project at the Pre-design stage.

CASBEE for New Construction
This is a self-assessment check system that allows architects and engineers to raise the BEE value of the building under consideration during its design process. It makes assessments based on the design specification and the anticipated performance. It can also serve as a labeling tool when the building is subjected to expert third-party assessment. Remodeling and replacement construction are evaluated under "CASBEE for New Construction."

CASBEE for Existing Building
This assessment tool targets existing building stock, based on operation records for at least one year after completion. It was developed to be applicable to asset assessment as well.

CASBEE for Renovation
There is growing demand for building stock renovation, especially in Japanese market. In the same way as "CASBEE for Existing Building," this tool targets existing buildings. It can be used to generate proposals for building operation monitoring, commissioning and upgrade design with a view to ESCO (Energy Service Company) projects, which will be increasingly important in future, and for building stock renovation. This tool is designed for ascertaining the degree of improvement (increased BEE), relative to the level that preceded renovation. Labeling is also possible by third-party agencies.

CASBEE for Specific Purposes

The basic CASBEE tool suite is applicable to a diverse range of individual applications.

(1) Application to buildings for short-term use
The tool "CASBEE for Temporary Construction (exhibition facilities)," published in July 2004, was developed as an extension to CASBEE for New Construction for evaluating temporary buildings constructed specifically for short-term use, such as Expo pavilions. Buildings of this type have short-term lifecycles, and therefore consideration must concentrate largely on material use and recycling in the construction and demolition phases. Also, these buildings have simple equipment and interior and exterior finishes. The scoring criteria reflect those features of this type of buildings. So far, the tool has been completed in a version limited to exhibition facilities.

The current version of CASBEE for Temporary Construction (exhibition facilities) targets buildings that have lifetime within 5 years. Scoring criteria are based on those for halls of CASBEE-NC, and some modifications are made as follows;

1) The scoring criteria of Q-1 Indoor environment is lowered for background noise, because simple exterior materials with poor performance in sound insulation are often installed in temporally buildings.
2) "Durability & Reliability" and "Flexibility & Adaptability" in Q-2 Quality of service are excluded from scoring criteria.
3) In LR-2 Resource & Materials, "3R (reuse, reduction and recycling) of building materials" and "Minimization of waste disposal" are evaluated as additional assessment items.
4) Weightings are altered to reflect the importance of resource recycle and waste reduction in this assessment system. LR-2 gains heavier weight, and lighter weight is allocated for LR-1 Energy and Q-2 Quality of Service.

(2) Simple assessment
Assessment using CASBEE for New Construction may take 3-7 days, including the time required to prepare documents necessary as the basis for scoring. CASBEE for New Construction (brief version) was developed to meet the growing need for a tool to handle objectives such as those below. It makes a simplified, provisional assessment possible in around two hours (excluding time for the preparation of an Energy Saving Plan).

1) The need for simplified setting of the Building Environmental Efficiency level (as a tool for consensus forming between owners, designers and builders, etc.).
2) The need for setting environmental design targets and assessing attainment (as a proposal management tool etc. under ISO14001).
3) The need for preparation of documents for submission to government agencies, etc. (Environmental measures under construction administration, such as CASBEE Nagoya and CASBEE Osaka).

(3) Consideration for regional character
As noted above, CASBEE for New Construction (brief version) can be used by local authorities in construction administration. Local authorities that use this tool can tailor it to local conditions, such as climate and prioritized policies. Changes are generally made by modifying the weighting coefficients. Such assessment can be made mandatory in the same way as an Energy Saving Plan, to be submitted to the authorities together with the building approval application, as a way to improve the environmental efficiency of buildings in the region. Flexible response to regional character is a common feature of all elements of the CASBEE family.

One example is "CASBEE Nagoya." CASBEE Nagoya has its own scoring guidelines that instruct some criteria in relation to local contexts, such as materials from local industry, and that define some excluding criteria. After CASBEE Nagoya began on April 1, 2004, the city received about 30 reports as of the end of July, and most of those buildings were labeled as class "B^-" or "B⁺." Also almost no confusion was reported to the municipality over the operation of the system (Noda, 2004). It shows that the system effectively works for local application, so far.
Another example is CASBEE Osaka that altered weighting coefficient from the original to reflect the high priority they give to heat island policy. The city of Osaka also started administrative use of CASBEE from October 1, 2004, changed the weights of Q-1 Indoor environment from 0.4 to 0.3 and Q-3 Outdoor environment on site from 0.3 to 0.4.

(4) Detailed assessment of heat island impact
Assessment of the heat island effect is essential in major urban areas, such as Tokyo and Osaka. CASBEE-HI (CASBEE for Heat Island Relaxation) was developed to assess efforts in buildings to alleviate the heat island effect. Its role is to make a more detailed and quantitative assessment of the heat island-related assessment items included in the basic tools.

(5) Extended tool for regional scale assessment
CASBEE considers individual buildings, but it fully recognizes the importance of assessing building groups. Many recent city-center redevelopment projects have included plans taking into account the urban surroundings as one unit. For example, provision of public spaces on the site can be expected to have a positive effect on the surrounding environment, thereby improving environmental quality and performance (Q). Common restrictions imposed on all buildings on a site, even if each one has a different owner, can be regarded as efforts to improve the environmental performance of the urban area as a whole.
CASBEE-UD (CASBEE for Urban Development) was developed to assess the efforts of city-center renewals in urban districts or development of large areas including multiple buildings.

(6) Assessment tool for detached houses
CASBEE's basic tools can assess a large apartment house, but not a small detached house. CASBEE for Home (Detached Houses) has been developing to assess detached houses.

Table.1 Expansion of CASBEE for specific purposes (as of July 2006)

Project Organization

Research and development of CASBEE have been carried out as a cooperative project between industry, government and academia with the assistance of Japanese Ministry of Land, Infrastructure and Transport. Newly-formed JSBC (Japan Sustainable Building Consortium) and its affiliated sub-committees provide overall management of CASBEE, and the secretariat is set within the Institute for Building Environment and Energy Conservation.

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Copyright (C) 2006 Japan Sustainable Building Consortium (JSBC), All Rights Reserved