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.

The present paper investigates, both experimentally and by simulation, the influence of faulty VAV units that do not affect the zone temperature on total energy consumption of a VAV system. In an experimental room, the respective total energy consumptions of both normal operation and faulty operation were measured. The results indicate that a faulty unit affects other normal units, causing an energy waste of approximately 20-50%.

Numerous problems can occur for an investigator of larger datasets, e.g. how to handle dimensionality, many variables and few observations, few variables and many observations, correlations, missing data, noise and to extract information from all data simultaneously. Multivariate analysis (MVA) is an established method for dealing with such problems. In this work, we introduce a methodology based on MVA, which was developed to model the building energy performance from the perspective of the property holder.

The building simulation tool Domus has been recently renamed as PowerDomus for whole-building hygrothermal and energy simulation. Enhancements have been accomplished by improving the features for input and output data applied to multizone buildings, by adding HVAC systems and plants, by adding attics among other Graphical User Interface (GUI) features and by improving the numerical algorithms for calculating Sun angles, shading projections and moisture prediction through composite walls using moisture content as driving potential.