ventilation rates

The steady-state concentration of occupant generated carbon dioxide (CO2) is used in some applications as an indicator of compliance with a required ventilation rate. These applications assume that the CO2 is at a uniform concentration in the space being considered, and that the outdoor concentration, ventilation rate, and CO2 emission rate are all constant. Emission rates are often derived using an equation in the ASHRAE Fundamentals Handbook, which is poorly referenced and not based on the most recent understanding of the principles of human metabolism.

Ventilation in dwellings is likely to be impacted by configurations of windows and internal doors, but there is little empirical research investigating this in occupied homes. Closure of internal doors will affect noise, light, heat flow and how air moves into and through a building, as well as the volume of air in which pollutants are diluted.

Use of Demand Controlled ventilation (DCV) can potentially save more than 50% of energy use for ventilation purposes compared to constant air volume (CAV) ventilation. Correct and updated calculation of preset minimum (Vmin) and maximum (Vmax) airflow rates are important to maximize energy saving and to ensure good indoor quality. Furthermore, earlier studies have shown that controlling units' ability to actually handle V min is lacking and causes instability in the DCV systems 

In an extensive simulation study using a multi-zone airflow and contaminant transport calculation software (CONTAM) recommendations for the supply air rates for residential housing were derived as input for the revision of the Austrian standard ÖNORM H 6038 (2014). The floor plan, the occupancy and the contaminant and humidity sources are modelled to represent a typical Austrian housing situation. A humidity buffering model is also implemented. Based on common thresholds for CO2, relative humidity (r.h.) and TVOC the so-called relative threshold deviation is determined.

As natural wind is continuously fluctuating in both speed and direction, quantifying instantaneous wind-driven natural ventilation rate can be difficult, and often an average effect is used to stabilize the fluctuations. This work performs an experimental investigation to assess the validity of assumptions often used in quantifying airflows through an opening under cross natural ventilation condition. In the experiment, the three velocity components are analyzed for flows approaching and through an open window exposed to natural wind.

This paper presents some results from the Work Package 5 in the HealthVent project supported by the European Commission. One of the objectives of the project has been to review and critically evaluate the existing requirements on ventilation and IAQ defined in national building codes and European standards. The project’s focus has been set on ventilation rates, pollutants, noise, temperature and draft in dwellings, offices, schools and kindergartens. This paper presents a summary of the values given in European regulations and results of comparisons.

Natural ventilation is an effective method for energy conservation while potentially improving indoor air quality. Furthermore, a window has a significant impact on energy consumption. The purpose of this study is to reduce building energy use by changing ventilation rates and window areas. We analyzed the energy consumption and CO2 emissions according to ventilation rates and window areas through using a computer program, HEED 3.0. The reference model had two windows of 1.2m×1.5m, and assumed there was no ventilation except for the minimum ventilation rate of 0.35 ACH.

This paper describes a series of field measurements investigating the ventilation rates and indoor airquality in four newly built secondary schools in England. In these schools each with a differentventilation strategy - measurements and calculations were performed to determine the variation inventilation rates during the school day. All the schools were assessed for compliance with the recentlyadopted Building Bulletin 101 which defines the set of criteria in relation to the ventilation rates andindoor air quality in new school buildings.

Background. A low ventilation rate has been shown to increase the risk for health and comfort problems in offices. However, very few studies have investigated the impact of ventilation rate at home on health effects, (Wargocki et al. 2002). The aim of this study was to investigate if low ventilation rates in homes do increase the risk for asthma and other allergic symptoms among pre-school children in Sweden.

Badly designed stables may affect the animals' health, but it is difficult to design a stable with acceptable ventilation rates and indoor comfort without the right tools or guidelines.For the design of animal housing facilities, the authors used the passive building simulation tool QUICK II, extended with a natural ventilation model, and an animal heat generation model.