IBPSA2013

Many European countries assess the heating and cooling needs of buildings using the quasi-steady state calculation method described in EN ISO 13790. The energy need is calculated by establishing the monthly balance of heat losses and heat gains, and the dynamic effects are taken into consideration by introducing correlation factors. The difficulty of evaluating night-time ventilation with such a method comes from the strong influence of the dynamic effects.

A building life cycle simulation tool has been developed and linked to thermal simulation, allowing energy use and other environmental impacts to be evaluated. Existing building LCA tools are based upon a static method, considering yearly average processes and impacts. A dynamic method has been developed here in order to model the time variation of electricity production and allocate environmental impacts to different uses. Results on a case study show an increase of environmental impacts up to 40% compared to the common static method.

The majority of numerical studies of room airflow using Computational Fluid Dynamics (CFD)  are conducted with the steady Reynolds-averaged Navier-Stokes (RANS) approach. In this approach the averaged quantities are computed, and the effect of turbulence is modelled. Furthermore, the standard-gradient diffusion hypothesis is often used to model the turbulent mass transport, which relates the turbulent mass flux to the mean concentration derivative.

ANSI/ASHRAE Standard 140, Standard Method of Test for the Evaluation of Building Energy Analysis Computer Programs applies the IEA BESTEST building thermal fabric test cases and example simulation results originally published in 1995. These software accuracy test cases and their example simulation results, which comprise the first test suite adapted for the initial 2001 version of Standard 140, are approaching their 20th anniversary.

Multidimensional effects through porous building elements is barely explored in the literature due to many difficulties such as modeling complexity, computer run time, numerical convergence and highly moisture-dependent properties. Furthermore, when the multidimensional effect is considered, thermal bridges may play an important role on the hygrothermal building performance due to local increase of heat and mass flux densities.

Windows are the only part in buildings that can directly penetrate the solar radiation into the space and thus the shading devices are needed to control the solar penetration. In this study, optimized slat angle control strategies of venetian blinds are suggested. In the development process of the slat angle control strategy, annual cooling, heating, lighting energy and Daylight Glare Index performances are evaluated for each slat angle in the first hand, and then those comprehensive performances are categorized under different window solar radiation regions with the increment of 100 W/m2.

Model Predictive control is an advanced control tech-nique that has been used to optimize thermal comfort in buildings. Nowadays, the new buildings are char-acterized by an important inertia as well as low power heating systems. Since the thermal losses are very low, taking into account the intermittent occupancies in the control strategy is questionable. More precisely, in this paper, two model predictive controllers are devel-oped to reduce energy consumption while preserving the thermal comfort.

This paper reports on a study of the thermal performance of two-storey apartments in Adelaide, South Australia. The overall design achieved an energy rating score around 7.5 Stars in the Australia’s National Home Energy Rating Scheme (NatHERS); however, without air-conditioning some of the spaces were considered too warm during hot weather. Aspects of the building design and operation that contribute to poor performance are investigated.

Some building performance simulation programs compute the volume flow rate in ducts and pipe net-works for a given fan speed, which may be computed by a feedback controller, based on the intersection of the flow resistance and fan curve. We show ana-lytically and based on numerical simulations that fan models that use affinity laws and polynomials for the fan curve can lead to equations that become singular, have no, one, multiple or an infinite number of solu-tions.