DESIGO Energy-efficient applications: TABS Control Application datasheet Answers for infrastructure.
Table of contents 1 Brief introduction to TABS Control .......................................................5 2 Basics.......................................................................................................6 3 TABS control ...........................................................................................8 3.1 Overview ...................................................................................................8 3.2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.
1 Brief introduction to TABS Control Thermally activated building systems (TABS) refers to heating and cooling transmission systems taking advantage of large surface areas and integrated in the building structure. These type of systems take advantage of a building's mass, usually structural floors and slabs to thermally condition a building. Either TABS alone, or TABS supplemented by auxiliary systems, heats or cools the space.
2 Basics Ever greater demands placed on room conditions, as well as a growing awareness of the need to reduce energy consumption, demand new forward-looking building concepts. Thermally Activated Building Systems (TABS) is an innovative technology that rises to the challenge. Thermally activated building systems (i.e. typically the building structure) are considered a targeted part of energy management to increase energy efficiency.
– Energy efficient, self-regulating heat and cold generation control of the room temperature. – Low building and maintenance costs. Constraints – Additional inertia caused from ceiling/flooring, e.g. raised floors, suspended ceilings or insulation must be considered. – Thermal comfort cannot be adjusted to suit everyone: a certain level of roomtemperature fluctuation throughout the day must be expected.
3 TABS control 3.1 Overview TABS require special control for zones, energy generation and distribution. They can be dealt with in the same manner as for other heat and cold transfer systems. Zone control distributes heat and cold within a TABS zone based on demand. The same flow piping generally supplies multiple rooms, i.e. the rooms are grouped into zones. The TABS control application controls the flow temperature for a zone dependent on climatic conditions using two modulating valves and a pump.
3.2 The principal functions 3.2.1 Heating and cooling curve module Advantages: – High level of room comfort. – Fully automatic changeover between heating and cooling. – Permits/disables general heating or cooling operations dependent on outside temperature. – Scheduled shift of flow temperature setpoints (e.g. weekend operation). The innovative heating and cooling curve module controls flow temperature for one heating circuit.
3.2.2 Sequence control module Advantages: – Demand-dependent changeover between heating and cooling mode. – No simultaneous heating and cooling. – Supports purge function for energy-efficient cycle operation. The sequence control module controls valves and pumps for the heating and cooling mixing circuit. This type of control was predestined for a hydraulics topology that allows the zone to draw hot or cold water and control the flow temperature via separate heating and cooling valves.
3.2.4 Cycle operation module (Energy efficiency module) Advantages: – Tremendous potential to save electricity by reducing zone pump operation: up to 60% savings in electricity is possible. – Efficient use of natural and less-expensive energy sources. Buildings featuring TABS offer energy efficient operation by design, and energy efficiency is the focus of tested (and proven) DESIGO applications.
4 Energy savings The energy efficiency was investigated as part of comprehensive simulations. The following is a brief summary of the results of a case study conduced jointly with the EMPA (Swiss Federal Laboratories for Materials Science and Technology). The study confirmed that operating a TABS building using DESIGO TABS control is very economical without sacrificing comfort. The simulations corresponded to a typical office building in the Zurich region.
5 Planning manual: TABS control Additional details on TABS control are available in the planning manual which is a joint product of Siemens BT and EMPA (Swiss Federal Laboratories for Materials Testing and Research) http://www.empa.ch . The manual provides professional engineers, builders and operators with a comprehensive description of methods and solutions to design, control and operate TABS technologies.
7.2 Customer benefits – Energy use reductions result in cost savings. – Sustainable reduction of CO2 emissions through the efficient use of thermally activated building systems. – Time and costs savings during engineering, commissioning and occupancy phases as well as lower service costs thanks to tested applications and detailed documentation. – Reduced maintenance services result in lower operating costs.
9 Display and operation Prepared plant diagrams as well as views for operation and monitoring are already available for the TABS application as part of DESIGO INSIGHT. Figure 9-1 Overview featuring the main plant and details for optimized plant operation. 10 System hardware The TABS control application is approved for installation on the primary automation station PXC. 11 Field devices Siemens field devices or equivalent products should be used whenever possible.
13 Comprehensive operation TABS control is an important element for the successful operation of a TABS building. The DESIGO system ensures comprehensive energy efficiency from generation to consumers. Multi-facetted applications, including: – Heat pump integration and control. – Coordination of cooling towers. – Shading system control. – Auxiliary system control. guarantee safe and reliable operation throughout the entire plant life cycle.
14 Appendix 14.1 Plant components The TABS control application is modular in design with variants and options in the widest possible range to customize the application.
14.2 Supported and recommended hydraulic circuits The application supports all hydraulic circuits that allow a virtually constant flow through TABS when the zone pump is switched on as well as for flow temperature control that heats or cools based on demand. Hydraulic circuits with common zone return piping may result in considerably more energy costs versus circuits with separate zone return pipes (see Table 14-2) due to losses from mixing.
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