Comparative review of existing certification programs and performance assessment tools for residential buildings

Architectural Science Review, March, 2005 by Miljana Horvat, Paul Fazio

Several existing certification programs and assessment tools that evaluate housing performance are presented in this paper, showing that there is global trend in defining and evaluating the overall building performance. Some programs are focusing on selected aspects only, such as energy efficiency and quality of materials and workmanship, with only PASS and FAIL categories of assessment. Others evaluate environmental impact of the building by introducing weights to the achieved scores, and by that, they reflect priorities among the parameters. This comparative review presents the state of the art in this field, helps identify the knowledge gaps and research needs, and, finally, serves as a starting point in the development of Canada's evaluation protocol and performance assessment tool for light-frame building envelopes used in residential buildings.

**********

Introduction

There is a global trend in understanding and evaluating the total performance of buildings. In several countries such programs have been or are being developed in an attempt to assess the issues that influence the performance of the building itself and, in some cases, to assess the impact of the building on its surrounding. Besides the assessment, their objective is to aid designers in their decision making process, in order to achieve failure-free, durable, healthy and environmentally friendly buildings. Even though this trend started as an evaluation of commercial buildings, in recent years the performance evaluation of housing is also included. Some programs were even developed specifically for housing.

This paper focuses on certification programs that deal with evaluation and assessment of housing. It serves as a starting point in the development of Canada's own evaluation protocol and performance assessment tool for housing. The need for developing a similar kind of evaluation program that can possibly lead to a quality certification was voiced by Canadian manufacturers and exporters of prefabricated houses in a survey conducted jointly by researchers at Concordia University and Forintek Canada Corp., which resulted in the report entitled: The Assessment of the Prefabricated Building Industry [1]. It was considered that recognition of superior quality in terms of performance, materials and workmanship would be an asset in marketing the product for domestic and, particularly, export markets, where Canadian house manufacturers must compete with their Swedish, Japanese and American counterparts.

Different programs deal with the issues differently: some are more performance oriented, and others can be strictly prescriptive. Some of them focus on evaluating the performance of only selected aspects, such as energy efficiency and quality of materials and workmanship, i.e. Swedish P-mark, Canadian R-2000, Quebec's Novoclimat, US Energy Star[R], with only PASS and FAIL categories of assessment. Their advantage is that they focus on conventional practices and are, therefore, more likely to be immediately applicable in the housing industry that can otherwise be very conservative. (1) Other programs, such as UK's BREEAM, USLEED[TM], Japan's CASBEE and international GBTool programs evaluate the environmental impact of the building and its level of sustainability. Even though the sustainability is not the main focus of this research, these programs are relevant for this project because they introduce different methods of assessment that lead to more efficient performance of the building. Their outcome usually results in several categories of performance and, thus, building rating systems. Therefore, they provide valuable base knowledge for the future development of Canada's own assessment tool.

While some of these programs, such as Swedish P-mark and Canadian R-2000 program have been in use for several years, others, like Japanese Housing Quality Assurance Law (HQAL), European Community's ETAG 007 and Quebec's Novoclimat are in the stage of finalisation and/or early implementation; therefore there is not sufficient information on the results of their application.

Programs and Tools

P-mark system (Sweden)

The P-mark system is a voluntary program that was established in Sweden in 1989 at the initiative of manufacturers of factory-made houses who wanted the certification program to cover the design stage as well as the performance of the finished house. (2)

P-mark is a comprehensive quality assurance program, backed up by inspections, which takes advantage of prefabrication to streamline quality control procedures. Besides performance requirements for finished house, it covers quality system, quality plan and supervisory inspections by National Board of Physical Planning and Building--Statens Planverk (SP). Some of the performance requirements for the finished house include air-tightness of the building envelope, air exchange rates, air-tightness of ducts, sound pressure levels, heat requirement and mean U-value, thermal comfort and radon concentration. For each requirement, there is a test method for verification of compliance. The P-mark system also gives the design rules for crawl space and concrete slab foundations, basement walls, external walls, kitchen, bathrooms, etc. In addition to this certification, SP authorities carry out unannounced factory inspections twice a year. They also inspect and conduct measurements in about 5% of the finished houses, randomly chosen. In these inspections, the following points are tested: air-tightness of the house, air-tightness of ventilation ducts, ventilation. Inspections cover the performance of the heating and ventilation system and the quality of work in toilets and kitchens to prevent water leakage [4].