IBPSA2005

In this paper we emphasize a technique based on graph theory that allows for deriving both a dimensionally reduced object model required for setting up a thermal multizone model and a geometrical model for defining a single or multiple CFD domains in a building model together with incidence matrices correlating these models. The incidence matrices are an essential precondition for establishing a runtime coupling between both approaches such as automatically providing a CFD model with boundary conditions obtained during a thermal multizone simulation and vice versa.

This paper deals specifically with analysis of the thermal, airflow and daylighting performance of the façade elements and in particular with the Double Skin Façade (DSF) applied to the south and southeast facing office spine of a laboratory building. DSF have been applied successfully in Europe for a number of years with the desire to create a more natural internal climate, good daylight quality and access to outdoor air.

The paper describes a process that efficiently supports the early building design stage with prototype tools to capture topological floor plan sketches, calculate geometries, explore design alternatives, and generate data for performance simulations, for example for EnergyPlus. It is also shown how such data are used to generate object-model based simulators in the Virtual Building Laboratory environment. Examples and preliminary efficiency data are presented.

This work presents a simple design tool for the consideration of solar rights in urban design that was developed by the use of the computer model SustArc (Capeluto and Shaviv, 1997). This simple design tool allows the generation and evaluation of building configurations, ensuring solar rights of each neighboring building, as well as those of open spaces among them, by using the concept of solar envelopes without the need to be familiar with any specialized software.

This paper presents an air cooled slab system (ACS) specially designed for use in multi-storey steel framed buildings. The system works by passing air through ducts in the trapezoidal hollow section of the steel/concrete composite floor, so the mass of the concrete slab can be used to store both heat and coolth at different parts the diurnal cycle. Since the ACS system uses the thermal capacity of concrete, it has considerable potential for reducing or even eliminating the need for mechanical cooling.

Geothermal district heating systems (GDHSs) are modeled by examining the relations between thermodynamic losses and capital costs for the devices comprising the GDHSs, and some possible generalizations are proposed relating thermodynamic losses and capital costs. The model proposed is then applied to a GDHS installed in Turkey using actual data. Finally, the results are discussed in terms of the identification and evaluation of inefficiencies in the system and of possible improvements.

The thermal modelling of windows is often carried out at a high level of precision whilst irradiance anddaylight quantities are predicted using coarse approximations. This paper describes a new approach to predict the daylighting and thermal performance of buildings with shading devices using a hybrid dynamic lighting-thermal model. Irradiation and daylighting modelling is carried out using the validated Radiance lighting simulation program. The irradiance predictions coming from raytracing calculations on virtual photocells provide input to a simplified thermal response model.

During a design stage building designers have to do many decisions that will influence an energy consumption in a designed building. Investments to a building structure and HVAC system are a basis for a low consumption of an energy. The decision making process is considered as the system of investment decisions where one certain decision is a project. The program has been developed for the selection of solutions for defined restrictions. One example is presented for the evaluation of different possible combinations of energy saving projects in a real building. 

Computational Fluid Dynamics (CFD) has evolved from an academic tool to an important commercial design tool over the past decades. In the present paper the accuracy of two equation turbulence models for 3-D internal air flows is investigated in terms of mean quantities and topological aspects. Results for pseudo 2-D and full 3-D simulations using the k-ε model and the Baseline (BSL) k-ω model of Menter, respectively, are compared with LDA measurements (Nielsen, 1990) and PIV measurements (Pedersen & Meyer, 2002).

Horizontal diffuse illuminance and direct illuminance were estimated by measured sky luminance distribution to investigate the consistency among global, diffuse and direct illuminance for a long-term IDMP data in Kyoto, Japan. In order to estimate the diffuse and direct illuminance by sky luminance distribution, it is necessary to identify the direct circumsolar region of the sky. This study introduced a new method to identify the direct region by comparing the measured diffuse illuminance and the calculated illuminance came from outside the supposed region.