Simple Access to Thermal Analysis Information (SABLE/SATAI)

Draft 1.0 – 27th nov. 2002

Background

The aim of the SABLE project is to provide an easy and simple access from AEC/FM domain specific software applications to IFC model server.

The specific need for Thermal Analysis software is to access to the specific information in a building project model to be able to calculate thermal loads.

The most important part of the model that should be exchanged between the model servers and such an application is:

• The building
• Building element geometry and properties
• Space geometry and properties

The exchange of detailed building element data relies on element types that are agreed upon in each building project. The details about these types are not exchanged using IFC; only the type 'name' is exchanged.
Applications that calculate thermal loads are able to calculate requirement values for the HVAC systems, such as the maximum air flow rate for a specific space, and write this information back to the IFC model.

Sub-Project Objectives

The present sub-project proposes to give the possibility for Thermal Analysis applications to access simply and easily to the following information within an IFC based building model:

• Simplified and identified geometry for walls, spaces, windows, doors, slabs and roofs
• “Thermal” space boundary surfaces geometric definition
• Topology information as known as relations between space – space boundaries – building elements (such as walls, spaces, windows, doors, slabs and roofs)
• “Thermal” space boundary surfaces physical property information (such as materials, layers, flag external/internal/underground, etc…)

Such Thermal analysis applications also require populating back the building model in terms of calculation results. For that, this project will also enable to write back the following information:

• Thermal coefficient of transmission for each thermal surfaces
• Maximum air flow rate for each spaces
• Etc …

In the context of SABLE the main tasks of this sub-project will be to define and implement a web service enabling Thermal Analysis application to access and write the information previously described.

Sub-Project Main Tasks

T1- Specification of the Thermal Analysis Web Service (TAWS) architecture

The purpose of this task is to defined the software architecture needed to:

• Extract the Thermal analysis specific information from an IFC model server
• Expose the information in a simple way to the Thermal Analysis client application through Web Service Methods
• Write the thermal calculation results through web services methods

T2- Geometric algorithms

The purpose of this task is to define and implements any geometric algorithms needed to generate the Thermal Analysis information such as:

• Geometry of building elements and spaces
• Geometry of “thermal” surfaces (spaces boundaries)
• Etc …

The aim of these algorithms is to run on the SABLE server.

T3- Information extraction algorithms

The purpose of this task is to define and implements any information extraction algorithm from the IFC model information needed to expose to the Thermal Analysis information such as:

• Material information
• Topology of spaces
• Etc …

T4- Specification of the SOAP messages between TAWS and the client

The purpose of this task is to specify the XML structure of the SOAP messages that will transmit the request from the client application to the TAWS and the answers from the TAWS to the client.

T5- Specification and implementation of a program language specific API (Optional)

If needed, the purpose of this additional task is to provide for the Thermal Analysis application developer an API that wraps the SOAP layer and exposes simple methods and object to request and send the information from and to the TAWS.

Deliverables

This SABLE sub-project will deliver:

• The Thermal Analysis Web Service as a middleware to access/write to the IFC building model information stored on IFC model servers,
• A document describing how to use this web service / middleware,
• Optionally, an Application Programming Interface that wraps the SOAP messaging system to implement directly in the Thermal Analysis client application.