A novel low pressure technique for measuring the air tightness of buildings.

一种用于测量建筑物气密性的新型低压技术。

• 批准号: EP/H023240/1
• 负责人: Edward Cooper
• 金额: $ 12.72万
• 依托单位: University of Nottingham
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2010
• 资助国家: 英国
• 起止时间: 2010 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FH023240%2F1
• 关键词: novel; low; pressure; technique; measuring

The importance of energy efficiency of buildings has been acknowledged in the UK in recent years by the Code for Sustainable Homes and substantial improvements to the Building Regulations. The adventitious leakage of buildings has received particular attention as standards in the UK have for many years been relatively poor. Most new buildings now have to show satisfactory levels of airtightness to comply with the Regulations. The airtightness of a building envelope is allied directly to the efficiency of the space conditioning, which is typically the main energy use. Therefore, reducing adventitious leakage can make a significant reduction in energy consumption. The method used presently to ascertain compliance with the Regulations is called the steady pressurisation technique. This technique has been used globally for many years, but does have a number of deficiencies; namely the difficulty and expense of testing large buildings, uncertainties due to wind and buoyancy factors, uncertainties due to experimental and measurement errors, and its inability to obtain results in the range of naturally occurring pressure differences.A novel technique is being developed at the University of Nottingham which accurately relates a known volume pulse to flow through the building envelope at pressures typically found in infiltration, hence significantly improving on the current steady technique. The underlying principle of the technique is to subject the building envelope to a known volume change in a short period of time (i.e. 1.5 s). This generates a flow rate through the adventitious openings that in turn creates a pulse in the internal pressure, characteristic of the building's leakage. The basic pulse concept has been tried previously by others, but has never before been made to work. There are three key novel features that have led to its success this time. The first is to measure the pressure difference across the building envelope a short time before and after the pulse, thereby allowing wind and buoyancy effects to be largely eliminated. The second is to generate a pressure pulse in such a way that a period of quasi-steady flow is obtained, thereby eliminating inertia effects associated with unsteady flow. The third is to minimise the variation of the pressure difference during the quasi-steady period such that flexing of the building envelope is not a problem. The quasi-steady period gives directly the leakage characteristic at low pressure and after adjustment to still air conditions and a small correction for the effective flow rate arising from compressibility of the air it can be plotted in the same way as the steady technique. Work to date has focused primarily on using a piston and cylinder to generate the volume pulse. This has worked well but preliminary tests have shown that a simpler, more portable design using a nozzle may also be possible. The first aim of the proposed project will be to research the piston technique further, as testing and analysis of specific factors is still needed to remove uncertainties. The second aim will be to explore the concept of a nozzle pulse technique. This has the most potential for marketing as a low pressure leakage tester, as it would make the system even more compact and portable, hence saving transport costs and space. To date, however, it has not been possible to measure the volume change accurately. It is intended to conduct a theoretical investigation of how this may be done and then, if the theory suggests it is possible, test it experimentally. The increased demand for leakage measurement coupled with the deficiencies of the conventional method means there is a genuine need for the described technique. The technique will be quicker, cheaper, more portable and more accurate than the conventional method. As such, the potential beneficiaries will be regulators, builders/developers, and leakage testing companies.

近年来，英国通过《可持续住宅规范》和《建筑法规》的大幅改进，承认了建筑物能源效率的重要性。由于英国多年来的标准相对较差，建筑物的意外泄漏受到了特别关注。大多数新建建筑物现在必须显示出令人满意的密闭性水平，以符合该条例。建筑围护结构的气密性直接关系到空间调节的效率，而空间调节通常是主要的能源使用。因此，减少非恒定泄漏可以显著降低能耗。目前用于确定是否符合规定的方法称为稳定加压技术。这种技术已在全球使用多年，但确实存在一些不足；即测试大型建筑物的难度和费用，风和浮力因素带来的不确定性，实验和测量误差带来的不确定性，以及无法在自然发生的压力差范围内获得结果。诺丁汉大学（University of Nottingham）正在开发一种新技术，该技术可以准确地将已知的体积脉冲与渗透压力下流过建筑围护结构的流体联系起来，从而大大改进了目前的稳定技术。该技术的基本原理是使建筑围护结构在短时间内（即1.5秒）发生已知的体积变化。这通过不确定的开口产生流速，从而在内部压力中产生脉冲，这是建筑物泄漏的特征。基本的脉冲概念以前已经被其他人尝试过，但从未成功过。这次的成功有三个关键的新特点。首先是测量脉冲前后短时间内建筑围护结构的压力差，从而使风和浮力的影响在很大程度上被消除。第二种是产生压力脉冲，从而获得准定常流动周期，从而消除非定常流动的惯性效应。第三是尽量减少准稳定期间压力差的变化，使建筑围护结构的弯曲不成问题。准稳态周期直接给出了低压下的泄漏特性，在对静止空气条件进行调整并对空气可压缩性引起的有效流量进行小的修正后，可以用与稳态技术相同的方法进行绘制。迄今为止的工作主要集中在使用活塞和气缸来产生体积脉冲。这种方法效果很好，但初步测试表明，使用喷嘴的更简单、更便携的设计也是可能的。拟议项目的第一个目标将是进一步研究活塞技术，因为仍然需要对特定因素进行测试和分析，以消除不确定性。第二个目标是探索喷嘴脉冲技术的概念。作为一种低压泄漏测试仪，它具有最大的市场潜力，因为它将使系统更加紧凑和便携，从而节省运输成本和空间。然而，到目前为止，还不可能准确地测量体积变化。它的目的是对如何做到这一点进行理论研究，然后，如果理论表明这是可能的，就进行实验验证。对泄漏测量的需求增加，加上传统方法的不足，意味着对所描述的技术有真正的需求。这项技术将比传统方法更快、更便宜、更便携、更准确。因此，潜在的受益者将是监管机构、建筑商/开发商和泄漏测试公司。

项目成果

A progressive comparison of the novel pulse and conventional steady state methods of measuring the airtightness of buildings

测量建筑物气密性的新型脉冲方法和传统稳态方法的逐步比较

• DOI: 10.1016/j.enbuild.2022.111983
• 发表时间: 2022
• 期刊: Energy and Buildings
• 影响因子: 6.7
• 作者: Zheng X

Measurement of the adventitious leakage of churches with a novel pulse technique

用新型脉冲技术测量教堂的偶然泄漏

• 发表时间: 2011
• 作者: Cooper E W

Estimation of the infiltration rate of UK homes with the divide-by-20 rule and its comparison with site measurements

用除以 20 规则估算英国住宅的渗透率及其与现场测量的比较

• DOI: 10.1016/j.buildenv.2020.107275
• 发表时间: 2020
• 期刊: Building and Environment
• 影响因子: 7.4
• 作者: Pasos A

Field trialing of a new airtightness tester in a range of UK homes

在一系列英国家庭中对新型气密性测试仪进行现场试验

• 发表时间: 2015
• 作者: Cooper E

A Nozzle Pulse Pressurisation Technique For Measurement of Building Leakage At Low Pressure

低压建筑物渗漏的喷嘴脉冲加压技术

• 发表时间: 2014
• 作者: Cooper E