English

In Denmark, cooling of office buildings during summer contributes significantly to electrical consumption. The use of phase change material (PCM) can help to reduce overtemperatures during summer and even out temperature fluctuations over the day, hereby reducing both heating and cooling demands in buildings. This paper describes a numerical method for calculating the latent storage performance of building components containing PCM in order to evaluate the impact on heating and cooling demands.

Most of commercial buildings are intermittently operated in practice. The use of the Radiant Time Series (RTS) method based on the continuous air-conditioning operation could result in largely underestimated peak cooling loads, and inconsistent design. Hence, a new method is developed based on the RTS. The new method only needs one more step after the current RTS design procedure, using the overall periodic transfer coefficients that have computed in this procedure. The additional cooling loads generated by the new method well agree with the results form EnergyPlus simulations.

A mathematical model is presented to predict the behaviour of condensation and frost formation on heat transfer surfaces by simultaneously considering the condensing and frost layer. The model employs one-dimensional transient formulation based upon a local averaging technique, taking into account the variation of the frost density and thickness. The presented model is validated by comparing to experimental data provided by the dry cooler manufacturer. It is found that the model can predict the heat transfer performance of the dry cooler with an accuracy of within 2.19%.

In this work, we present a new managament strategy for a ground coupled HVAC system in a cooling dominated office area. The idea is disminish the electrical consumption while keeping the thermal comfort requirements. This objective is achieved by means of the proper management of some parameters of the system: the air mass flow in the fan, the mass water flow in the internal and external hydraulic circuit and the set point temperature in the water to water heat pump.

This paper discusses the development of a new module in EnergyPlus that predicts the cooling performance of PDEC towers with sprays. It introduces an overview of PDEC towers and existing models. A simulation model is employed to design and evaluate PDEC towers, and its modelling algorithm in EnergyPlus is described. An analysis of the capability in different climates and the energy performance of PDEC towers has been performed by using the model implemented, and the main results from various case studies are presented.

This study developed a component-based gray-box model for variable refrigerant flow (VRF) airconditioning systems to simulate and predict the performance and energy consumption of VRF system in cooling condition. Results from the testing of Daikin’s 10HP VRV system with six indoor units, as well as the manufacturer’s data, were used to fit the key parameters of each component in this VRF model. This model was integrated in the building energy simulation software DeST and was validated by using data both from Daikin’s product handbook and from tested results.

The present paper describes heat pump systems and their energy efficiency. In the first part of the paper the modelling of heat pump system is presented. In a second part a parameter study is discussed which takes into account the hydraulic circuit (serial / parallel hydraulic circuit of the storage tank) of the heat pump system and control strategies used for its operation.

Subtask 1 of the IEA ECBCS Annex 41 (IEA 2007) project had the purpose to advance development in modelling of integral Heat, Air and Moisture (HAM) transfer processes that take place in “whole buildings”. Such modelling considers all relevant elements of buildings: The indoor air, building envelope, inside constructions, furnishing, systems and users. The building elements interact with each other and with the outside climate.

Building physics processes in some parts and elements of revitalized historical buildings play an important role in their future energy efficiency and maintenance. The unique character of 100-years-old post-industrial buildings results from masonry-brick façades with precise ornamentation and sophisticated details which should be retained and reconstructed in renovation works. Any changes in wall properties, such as the addition of new layers (insulation, rendering or plaster), are at variance with cultural heritage protection.

This paper gives an onset to whole building hygrothermal modelling of the interaction between interior and exterior climates via building enclosures, which even takes into account wind-driven rain (WDR). First, the temporal and spatial distribution of WDR on the facades of a single leaf brick wall building is numerically determined. Then the hygrothermal behaviour of the walls and the room zone is numerically analysed. The results show that WDR loads can have significant impacts on the indoor climate, energy consumption and mould growth risk.