The impact of indoor thermal conditions,system controls and building types on the building energy demand

It is possible to evaluate the energy demand as well as the parameters related to indoor thermal comfort through building energy simulation tools. Since energy demand for heating and cooling is directly affected by the required level of thermal comfort, the investigation of the mutual relationship between thermal comfort and energy demand (and therefore operating costs) is of the foremost importance both to define the benchmarks for energy service contracts and to calibrate the energy labelling according to European Directive 2002/92/CE. The connection between indoor thermal comfort conditions and energy demand for both heating and cooling has been analyzed in this work with reference to a set of validation tests (office buildings) derived from a European draft standard. Once a range of required acceptable indoor operative temperatures had been fixed in accordance with Fanger's theory (e.g. −0.5 < PMV < −0.5), the effective hourly comfort conditions and the energy consumptions were estimated through dynamic simulations. The same approach was then used to quantify the energy demand when the range of acceptable indoor operative temperatures was fixed in accordance with de Dear's adaptive comfort theory.     

Enhanced supervision strategies for effective reduction of building energy consumption--A case study of Ningbo

The purpose of this paper is to investigate the reasons for ever growing energy consumption in buildings and to give enhanced supervision strategies for reduction of building energy consumption compared to regular ones. A case study of Ningbo city was used to make a detail analysis. Several factors were determined as the reasons for ever growing building energy consumption including climate change, household electricity load increase, the growth of real estate, fast-growing household electrical appliances, high energy consumption in existing buildings, changes in industrial structure and the lack of enhanced government supervision. Then the discussion of suitable countermeasures shows that only enhanced supervision strategies are currently applicable. Finally, it is concluded that enhanced government supervision strategies, including the establishment of a strict control system for new built buildings through information integration and encryption, establishing an energy efficiency supervision system of large-scale public building and a carrot-and-stick approach with added expert checklist for the building application of renewable energy, showed great advantages in promoting building energy efficiency in Ningbo, compared with other cities. These supervision strategies are applicable in other cities as they are in the similar situations in the enforcement of building energy efficiency.     

Development of Dutch occupancy and heating profiles for building simulation

Building simulations are often used to predict energy demand and to determine the financial feasibility of the low-carbon projects. However, recent research has documented large differences between actual and predicted energy consumption. In retrofit projects, this difference creates uncertainty about the payback periods and, as a consequence, owners are reluctant to invest in energy-efficient technologies. The differences between the actual and the expected energy consumption are caused by inexact input data on the thermal properties of the building envelope and by the use of standard occupancy data. Integrating occupancy patterns of diversity and variability in behaviour into building simulation can potentially foresee and account for the impact of behaviour in building performance. The presented research develops and applies occupancy heating profiles for building simulation tools in order create more accurate predictions of energy demand and energy performance. Statistical analyses were used to define the relationship between seven most common household types and occupancy patterns in the Netherlands. The developed household profiles aim at providing energy modellers with reliable, detailed and ready-to-use occupancy data for building simulation. This household-specific occupancy information can be used in projects that are highly sensitive to the uncertainty related to return of investments.     

合肥某高校图书馆空调能耗模拟及影响因素分析

结合空调室内外的设计参数,以合肥某高校图书馆为例,分析了不同空调运行模式及不同保温方式对空调系统能耗的影响,得出的结论为图书馆类公共建筑的节能设计、改造提供参考。     

Developing future hourly weather files for studying the impact of climate change on building energy performance in Hong Kong

The concern on climate change leads to growing demand for minimization of energy use. As building is one of the largest energy consuming sectors, it is essential to study the impact of climate change on building energy performance. In this regard, building energy simulation software is a useful tool. A set of appropriate typical weather files is one of the key factors towards successful building energy simulation. This paper reports the work of developing a set of weather data files for subtropical Hong Kong, taking into the effect of future climate change. Projected monthly mean climate changes from a selected General Circulation Model for three future periods under two emission scenarios were integrated into an existing typical meteorological year weather file by a morphing method. Through this work, six sets of future weather files for subtropical Hong Kong were produced. A typical office building and a residential flat were modeled using building simulation program EnergyPlus. Hourly building energy simulations were carried out. The simulated results indicate that there will be substantial increase in A/C energy consumption under the impact of future climate change, ranging from 2.6% to 14.3% and from 3.7% to 24% for office building and residential flat, respectively.     

Outcome‐based ventilation: A framework for assessing performance,health, and energy impacts to inform office building ventilation decisions

This article presents an outcome‐based ventilation (OBV) framework, which combines competing ventilation impacts into a monetized loss function ($/occ/h) used to inform ventilation rate decisions. The OBV framework, developed for U.S. offices, considers six outcomes of increasing ventilation: profitable outcomes realized from improvements in occupant work performance and sick leave absenteeism; health outcomes from occupant exposure to outdoor fine particles and ozone; and energy outcomes from electricity and natural gas usage. We used the literature to set low, medium, and high reference values for OBV loss function parameters, and evaluated the framework and outcome‐based ventilation rates using a simulated U.S. office stock dataset and a case study in New York City. With parameters for all outcomes set at medium values derived from literature‐based central estimates, higher ventilation rates’ profitable benefits dominated negative health and energy impacts, and the OBV framework suggested ventilation should be ≥45 L/s/occ, much higher than the baseline ~8.5 L/s/occ rate prescribed by ASHRAE 62.1. Only when combining very low parameter estimates for profitable impacts with very high ones for health and energy impacts were all outcomes on the same order. Even then, however, outcome‐based ventilation rates were often twice the baseline rate or more.     

A nodal thermal model for photovoltaic systems: Impact on building temperature fields and elements of validation for tropical and humid climatic conditions

This article deals with both an experimental study and a numerical model of the thermal behaviour of a building whose roof is equipped with photovoltaic panels (PV panels). The aim of this study is to show the impact of the PV panels in terms of level of insulation or solar protection for the building. Contrary to existing models, the one presented here will allow us to determine both the temperature field of the building and the electric production of the PV array. Moreover, an experimental study has been conducted in La Reunion Island, where the climate is tropical and humid, with a strong solar radiation. In such conditions, it is important to minimise the thermal load through the roof of the building. The thermal model is integrated in a building simulation code and is able to predict the thermal impact of PV panels installed on buildings in several configurations and also their production of electricity. Basically, the PV panel is considered as a complex wall within which coupled heat transfer occurs. Conduction, convection and radiation heat transfer equations are solved simultaneously to simulate the global thermal behaviour of the building envelope including the PV panels; this is an approach we call ‘integrated modelling’ of PV panels. The experimental study is used to give elements of validation for the numerical model and a sensitivity analysis has been run to put in evidence the governing parameters. It has been shown that the radiative properties of the PV panel have a great impact on the temperature field of the tested building and the determination of these parameters has to be taken with care.     

寒冷地区装配式超低能耗建筑外墙板拼缝断热桥技术研究

通过有限元二维传热模拟,对装配式超低能耗建筑外墙板拼缝处存在的热桥进行研究,探究发泡聚氨酯的填充位置与填充厚度对断热桥效果的影响.研究表明,当发泡聚氨酯填充于保温层中央和保温层靠近室内一侧时,填充厚度110 mm可实现断热桥要求,但后者通过墙板的热流量较前者提高了约6％,室内热损失更大.当发泡聚氨酯填充于保温层靠近室外...