District Heating and Cooling Building Connection Handbooks
Description of the project
The objective of this project is to substantially re-write the 1990 version of the "Handbook", using a European and North American perspective. The handbook will have two sections, one each for heating and cooling, prepared by different subcontractors. These subcontractors are drawing the information from different sources and different countries. The format will be similar to the original handbook. Case studies will be included.
With the implementation of new cooling systems both in Europe and the United States similar issues of interconnecting buildings to cooling networks have come to light. Since many of the building designs or modifications are carried out by engineers, not familiar with district energy, it is felt that an up to date handbook of district cooling building connections would find a receptive audience. This project deals with issues in which district cooling is being implemented and where getting good performance has been problematic in the past due to poor interaction between the district cooling system and the building.
Therefore, this district cooling report will cover the principles and overall design aspects as well as benefits of district cooling systems. This will include available cooling sources (including absorption cooling), distribution and customer installations. The customer installations section will concentrate (but will not be limited to) on the following items:
- Indirect/direct connections
- Reheating issues
- Building cooling system conversion/adjustment requirements
- Cascading energy stream possibilities
- Applicable typical schematics and figures (diagrams) will be included to support (visualize) the technical description.
Summary of the final report of the project
This report is intended to assist engineers and consultants in designing and implementing conversions of building HVAC systems to accept chilled and hot water from district energy systems. Building types that are addressed include residential, commercial, institutional and industrial. The practical guidelines provided are based on extensive conversion and operating experience. As well as highlighting the most cost effective approach to conversions, the guidelines ensure that technically sound systems are built.
The report looks at the fundamentals and principles of both district heating and cooling including energy sources, distribution and customer interface. Design considerations of these three main components of district energy are described, as well as the benefits that district energy can bring to the building owners, the municipality and the public.
Critical points in designing the interface between the building energy system and the district energy system (energy transfer station) are outlined and are intended for use in the design of new building systems as well as for conversions of existing buildings. Detailed schematics of energy transfer stations are shown illustrating all components, including control equipment, heat exchangers and energy meter. Energy transfer station performance is detailed with graphs showing the impact of various parameters within a district energy system. The report also highlights the considerations of design and operation of the secondary system or the system that uses the energy from the district energy system.
The report also breaks down, step by step, the procedure to convert a building to accept district energy. These include building survey and schematic design, energy consumption, compatibility, costs, system optimization, construction schedule, testing and commissioning. The suitability of a given system to be converted is also discussed.
The importance of a correct determination of the heating and cooling demand of a building is stressed, because a proper sizing of the heat exchanger in the energy transfer station affects the operation of the system in a major way. Several methods to determine this load demand value are described. The optimization of the heat exchanger is also very important because it forms a large part of the capital cost of the energy transfer station.
Some case histories of buildings connected to a district cooling system are described.
The CANMET Energy Technology Centre in Canada
Kattner/FVB in Edmonton, Canada
Sheffield Heat & Power Group, United Kingdom