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A large number of modern European buildings are equipped with ducted air distribution systems. Because they represent a key parameter for achieving a good indoor climate, increased attention has been given to their performance during the past fifty years. One aspect that is particularly developed in this handbook concerns the airtightness of the ductwork, which has been identified as a major source of inadequate functioning and energy wastage of HVAC systems. The investigations were carried out within the framework of the DUCT project (1997-1998) whose objectives are summarised as follows:
1. Quantify duct leakage impacts;
2. Identify and analyse ductwork deficiencies;
3. Propose and quantify improvements;
4. Propose modifications to existing standards.
The handbook is aimed primarily at policy makers, HVAC manufacturers and installers, maintenance contractors, architects, building managers, and building services engineers interested in ductwork performance. It focuses on sheet metal ducts that are mostly used in Europe although most of the information also applies to other types of ductwork systems (plastic-and-wire composite, fiberglass board, concrete, etc.). It includes expert knowledge derived from research and industry, as well as practical information based on surveys and field work. Calculation details are condensed to put the emphasis on end results and qualitative information.
The primary function of a building is to provide occupants with an environment that is suitable for their activities and well being. In fulfilling this role, outdoor perturbations and internal loads must be processed to achieve a good indoor climate. However, because there are a number of underlying issues, space conditioning in buildings has been given increased attention over the past few years. In fact, it is estimated that it represents about a quarter of the final energy demand in the EU. In addition, climate control is strongly related to public health and productivity concerns and recent studies suggest that it has an effect on measures of productivity such as absence from work or health costs. These usually lie between 5% and 15%.
In this context, the efficiency of air distribution systems is a very active field of investigation. These systems are often used in modern European buildings as a strategy to control thermal conditions and indoor air quality. Many problems have been reported in relation to energy use and peak power demand, clean air supply, flow balancing and airtightness etc. The purpose of this handbook is to give an overview of these aspects with a special focus on duct leakage and its consequences.
Although this topic of study has been visited in the late fifties in Sweden, leading to the first ductwork airtightness requirements in the Swedish AMA guideline in 1960, this concern seems rarely present today in most other European countries. In the context of energy conservation, sustainable development, and harmonisation of standards and regulations in Europe, this issue needs to be re-addressed to evaluate the implications of a tight air duct policy at the European level.
The contents of this handbook are briefly described below:
Chapter 1 Introduction;
Chapter 2 Overview of quality requirements of ductwork;
Chapter 3 summarises ductwork airtightness related standards in Europe and some other non European countries;
Chapter 4 looks at today's ductwork technology. It includes a review of ductwork construction, installation and rehabilitation techniques that may be used to limit duct leakage;
Chapter 5 is concerned with traditions in the design and installation of duct systems;
Chapter 6 deals with duct leakage field measurements in European countries. Little information is available on this subject, however, field data from the SAVE-DUCT project suggest that the ductwork airtightness is in general very poor;
Chapter 7 discusses the energy, indoor air quality and cost issues associated wit duct leakage. Sample calculations are performed based on realistic data;
Chapter 8 is dedicated to a macroscopic approach to the energy implications of a tight air duct policy at the European level;
Chapter 9 consists of a synthesis of issues brought to light by practitioners, manufacturers, and policy makers in the international seminar on ductwork airtightness held in Brussels June 10-11 1998.
Chapter 10 is more particularly geared towards the implementation of a tight air duct policy, with recommendations for technical and governmental measures.