A Study Of Demanding For Fresh Air In Residential Buildings

Since the 21 st century, with the gradual improvement of the quality of life, indoor air quality(IAQ) has received extensive attention. Introducing fresh air to the building becomes the necessary way to improve indoor air quality, widely adopted by many countries and regions of the world, and then written into in the relevant specification. However, the ventilation standards of each country are not exactly the same. Traditional theory of the ventilation rate is based on Yaglou(1936), People are regarded the main pollutant source in indoor air. But now building pollutions are considered in the contemporary theory, the aim of office building is to control the body odor, and the aim of residential construction is to meet the health indicators(concentration limit). ASHRAE Std62.1 and CEN set the ventilation rate should be determined by building and the number of indoor people. While British CIBSE Guide set the ventilation rate should be determined by occupant density or minimum ventilation rate. Germany DIN 1946-2 demands the indoor ventilation rate should maximize the personnel ventilation rate and building required ventalition rate. Japan’s method of building ventilation rate have clear requirements. GB50019-2003 chooses personnel minumum fresh air rate. New standard GB50736-2012 use per capita minimum fresh air volumn for public buildings and high personnel-density buildings, and residential buildings and hospital are set by air change rate.According to VOC emission database of building materials, two new method, characteristic and two-stage ventilation rate menthod, are proposed to predict vebtilation rate to improve the indoor air quality.This paper introduces three kinds of typical fresh air volume theory, and compares the new air volume index calculation method at home and abroad, for part of residential indoor test results of typical pollutants in the city has carried on the contrast analysis, it is concluded that the formaldehyde pollution is more serious, and a longer duration. With formaldehyde as control target, this paper established a typical model of residential construction, characteristic and two-stage ventilation rate menthod are used to calculate the reasonable range of the fresh air volume in residential indoor. The ventilation rate required for general residential indoor calculated by characteristic ventilation rate method is 0.39 ~ 0.91 times/h. Characteristic ventilation rate menthod may have overestimated the release quantity of pollutants in the process of sending out for a long time, the result value between the transient and steady state. Two-stage ventilation rate menthod emits 90% of release time for steady state period, in this state the air changes were 0.24 ~ 0.53 times/h, almost for half of the air changes calculated by characteristics ventilation rate method. The air changes needed for the unsteady stage is greater than steady-state phase required ventilation rate. It should be a reasonable selection of ventilation rate according to geographic and weather conditions when designing a ventilation system. When decorating a synthetic materials used it can choose larger air changes, when decorating simple or indoor as far as possible the natural materials used, it can choose low air changes.Based on the data of volatile organic compounds in the building materials, this paper discusses the required ventilation rate in residential construction by two methods, and proved the feasibility of the methods. However when determing the fresh air volume by this method, there are some uncertainty factors, need further experiments and discussion.