Simulation Study on the New Average Heat Flux Method to Determine U-Value of a Wall

The U-value is a very important parameter for evaluating the energy efficiency when refurbishing the existing buildings.Traditional in-situ test methods to determine the U-value usually require a very long time to filter weather fluctuations and other boundary condition influences.In this paper,the possibility of a new method to reduce the time necessitated for measuring the accurate U-value of a wall is tested.The proposed method recommends measuring the temperatures and heat flux on both sides of the wall and thereby utilising the average values of the internal and external heat flux to calculate the U-value.Under the idealised sinusoidal internal and external air temperature boundary conditions,four walls with different U-values were simulated according to the admittance procedure(AP).Results show that the proposed method could improve the maximum error level for most of the walls in consideration.It was not sensitive to the measurement start time and it was more stable even in less controlled boundary conditions involving large inner temperature variations or out of phase temperature waves.Besides,the error of the average heat flux method(within 10%)could be estimated earlier than that of traditional method.

Impact of UK Building Regulations on design and thermal performance of dwellings

This paper looks at the progressive impact of UK Building Regulations (Part L) on the energy consumption of dwellings with respect to thermal performance of the building envelope. It provides an overview of building legislation,highlighting progressive improvement in building elemental U-values and compliance methods. The focus centres on Building Regulations from 1965 to 2006,at a time when energy conservation has become an integral component of building control due to environmental concerns. Simulation software is used to compare energy consumption for 5 typical UK dwelling types through a series of case studies which illustrate the rate of impact over recent years.

A Study on Comparison of Building Energy Simulation and Measurement Results for a City Hall

In recent years, the number of public office buildings which were built by the glass curtain wall increased rapidly, but through the results of the investigation of the government, these buildings have been found that the heating and cooling load is high, and showed low energy efficiency. So in this study, through energy simulation, the energy consumption of public office building was verified and measured;environment data and calculated data were compared to make more precise simulation. The heating and cooling load was calculated via EnergyPlus;building was modeled by Google SketchUp connected to EnergyPlus. The results of this study were as follows: in simulation, incident solar radiation from large curtain wall should be underestimated. And using site-measured outdoor environment data can increase accuracy of simulation result.

Sensitivity Analysis of Building Envelop Elements Impact on Energy Consumptions Using BIM

Lots of researches?have shown that the optimization of building envelope reduces building energy consumption during its lifecycle. Due to the uncertainty of the relationship between individual design parameters and building performance, the extent of impact cannot be well-understood. Therefore, it is essential to evaluate the impact extent for different design parameters and identify the one (s) that impact (s) more to the building performance and hence focus so as to improve building performance efficiently. In the present research, main design parameters that affect the building performance are selected to analyse the extent of the impact. Material quantities are extracted directly from the Building Information Modelling (BIM) model so as to calculate the embodied energy in material. Moreover, simulation of energy consumption is run for different scenarios during operation stage. Energy embodied in typical construction materials are calculated for each scenario accordingly. Finally, sensitivity analysis is applied to find the extent of impact on life cycle energy of building for the selected design parameters in terms of both embodied energy (EE) and operational energy (OE). A case study of a manufactory plant is carried out to investigate the impact of the selected design parameters.

Lecablock, an Alternative Construction Material for the Exterior Walls of Passive House

In this paper it is attempted to investigate the Leca blocks as sustainable construction material for the exterior walls of passive house. The building physical properties of Leca design wall structure are studied along with the environmental impact and load-bearing capacity. To compare the results, a similar analysis is carried out considering the traditional wooden wall construction of passive houses. The results showed that Leca design wall structure can be an alternative sustainable solution to the traditional wooden wall structure of passive house, mainly due to its low U-value, its ability to handle moisture, and comparable structural load-bearing capacity. However, the wooden wall structure is more environmentally friendly than the Leca blocks due to its lower emissions to the environment and reduced energy use, especially during the manufacturing process.

A concept of capillary active,dynamic insulation integrated with heating,cooling and ventilation,air conditioning system

When a historic façade needs to be preserved or when the seismic considerations favor use of a concrete wall system and fire considerations limit exterior thermal insulation,one needs to use interior thermal insulation systems.Interior thermal insulation systems are less effective than the exterior systems and will not reduce the effect of thermal bridges.Yet they may be successfully used and,in many instances,are recommended as a complement to the exterior insulation.This paper presents one of these cases.It is focused on the most successful applications of capillary active,dynamic interior thermal insulation.This happens when such insulation is integrated with heating,cooling and ventilation,air conditioning(HVAC)system.Starting with a pioneering work of the Technical University in Dresden in development of capillary active interior insulations,we propose a next generation,namely,a bio-fiber thermal insulation.When completing the review,this paper proposes a concept of a joint research project to be undertaken by partners from the US(where improvement of indoor climate in exposed coastal areas is needed),China(indoor climate in non-air conditioned concrete buildings is an issue),and Germany(where the bio-fiber technology has been developed).