Noise Radiated by Circular Ventilation Ducts

Noise remains a major concern for building occupants, both in their home and workplace. Ventilation system is one of the noise sources in buildings. Usually, the main issue is the resulting noise level in the room. It is generated by the fan and the ductwork components, travels inside ducts, and is then radiated into the room by air diffusers, air inlets, and air outlets. But ducts also go through other indoor spaces. Airborne noise will pass through the duct wall and radiate in the surrounding space. This can be an issue for occupants. 

Rationale behind ventilation standards and regulations given by 20 countries

International there are many different requirements and regulations for ventilation.  Sometimes the variation is more than a factor of five. There are strong drivers to reduce energy consumption for HVAC, and therefore the spread in requirements and regulation is worthwhile to study. To reduce ventilation flows there is a necessity to understand the reasons behind. Demand control to reduce this flows is in many countries growing but the control parameters are quite different, for instance humidity versus CO2 control.

Diagnostic barriers to using PM2.5 concentrations as metrics of indoor air quality

Particulate matter with a diameter of ≤2.5µm (PM2.5) has been shown to be present in many buildings at concentrations that are harmful to human health. Accordingly, they should be used as metrics of indoor air quality (IAQ) and included in standards or norms. This paper uses measurements of PM2.5 concentrations made in three different environments using three different devices to show that there are barriers that must be before they can be considered viable diagnostics. Optical particle counters (OPCs) are a common device used to measure temporal changes in PM2.5 concentration.

How should we characterize emissions, transport, and the resulting exposure to SVOCs in the indoor environment?

A systematic and efficient strategy is needed to assess and manage the potential risks to human health that arise from the manufacture and use of thousands of chemicals.  For both volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs), exposure is strongly influenced by the types of materials and products in which the VOC or SVOC occur, the concentration of the VOC or SVOC in the material or product, the way in which the material or product is used or applied indoors, and the ventilation rate within the room or building.

IAQ in working environments in Belgium: alternative approaches to CO2 requirement

In March 2016 a new regulation came into force in Belgium regarding the wellbeing at work, with specific requirements on the indoor air quality (IAQ). The requirement is expressed as a maximum absolute CO2 concentration of 800 ppm in all working spaces. Compared to the previous requirement, i.e.

Ventilation requirements for different rooms as a result on the inquiries in 20 countries

As a result of new inquiries in 20 countries the ventilation requirements will be presented for different rooms in dwellings, offices and schools. These rooms are differentiated between wet rooms such as toilets, bathroom and kitchen and typical rooms for these buildings for instance classrooms and office rooms. The results show big differences between countries. Climate and building style can have an effect on ventilation requirements. Some countries have to only requirements for specific rooms but also for whole house and whole building ventilation.

Numerical and experimental identification of factors influencing the pressure homogeneity during an airtightness test in a large building

Airtightness is the most important property of building envelopes to understand the ventilation. Airtightness refers to the flow measurement through the building envelope as a function of pressure across the building envelope. This relationship often fits to a power law, which is the most common way of expressing data. However, pressure homogeneity during airtightness tests can crop up, especially in large buildings.

Uncertainties in airtightness measurements: regression methods and pressure sequences

This paper presents the results of a series of 30 fan pressurization tests in reproducibility conditions performed within a period of 10 days in October 2017. The tested unit is a newly constructed unoccupied apartment in Brussels. These results make possible to compare different regression methods and evaluate the impact of pressure stations chosen for these regressions.

Experimental Investigation of the Impact of Environmental Conditions on the Measurement of Building Infiltration, and its correlation with Airtightness

The air infiltration of a building, which fundamentally depends on its airtightness, can be a significant contributor to its heat loss.  It can also be affected by other factors such as external terrain, leakage distribution, sheltering factor and environmental conditions. The infiltration rate of a detached UK house was monitored for 2 months in early 2018 using constant concentration and decay tracer gas methods under various temperature and wind conditions.

Experimental study of enclosure airtightness of an outdoor chamber using the pulse technique and blower door method under various leakage and wind conditions

This paper introduces an experimental study of enclosure airtightness testing of an outdoor chamber using both the pulse technique and the blower door method.  This investigation is a 2nd stage comparison study following the previous testing of a house-sized chamber in a sheltered environment.  The outdoor chamber in this study has dimensions, approximately half that of a standard 20ft long shipping container.  Multiple openings were installed into the chamber’s envelope to provide a leakage level and characteristics similar to an average UK house.

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