PR2019

In recent years, many multi-type package air conditioning systems for buildings have become widespread in office buildings in Japan, and there are many cases where one air conditioning space is shared by using several indoor air conditioning units. The advantages of multi-type package air conditioning system are that it is possible to operate and control individually for each indoor unit, and that the user can arbitrarily change the temperature setting of the indoor unit.

Ventilation systems play an important role in providing a good indoor air quality in dwellings. Mechanical exhaust ventilation systems implement natural vents, also called trickle vents, to supply outdoor air to the dwelling. The airflow through these natural supply vents depends on the natural driving forces, i.e. wind and the stack effect, which vary in time.  

Japan will have to further reduce CO2 emissions to meet its obligations under the Paris Agreement negotiated at the 2015 United Nations Climate Change Conference. Society is increasingly demanding higher energy-efficiency standards and zero-energy buildings because general commercial buildings have high energy costs, especially for air conditioning.

Health Canada’s cross-Canada residential radon survey report from 2012 demonstrated that roughly 7% of Canadian homes contain radon levels above the Canadian guideline of 200 Bq/m3. The research outlined in this paper evaluates the effect of ventilation rates on radon levels in two homes located in Ontario, Canada. The first case study consisted of short-term (2 day) radon monitoring in a home using three ventilation strategies; one heat recovery ventilator (HRV) running, two HRVs running, and both HRVs turned off.

Radon gas is a well-known building´s pollutant which can affect negatively people´s health (WHO, 2009). Radon´s source is the soil underneath buildings. Radon moves from the soil to the buildings by advection through cracks and joints, and diffusion through porous materials. Once radon enters buildings it can accumulate in lower areas due to lack of ventilation. Ventilation is one of the main ways to prevent radon from accumulating in enclosed spaces in the case of moderate radon concentrations up to 600 Bq/m3 (Collignan, 2008). 

Indoor pollutants and particles pose a threat to human health as people spend 90% of their time in indoor spaces. A proper ventilation system should be able to remove indoor air pollutants, reduce particle depositions, at the lowest energy consumption by that system. In this work, particle concentrations and depositions are presented for two ventilation configurations (1) Displacement Ventilation (DV) and (2) the conventional ceiling supply and return.

The ventilation system removes pollutants effectively, and the resultant vertical temperature difference in the room greatly affects the indoor air distribution. A reasonable air distribution system is essential to provide a satisfying indoor air quality (IAQ) for the occupants, of which air quality in the breathing microenvironment plays a major role in occupant health, as they are exposed to this region directly.

Building dampness and mouldy indoor environments are associated with the increase of approximately 30-50% in variety of respiratory and asthma-related health outcomes through a meta-analysis. The indoor environment related to indoor dampness is not be revealed yet, however it is important to provide the architectural techniques and optimal occupant behavior for prevention of dampness in buildings. The authors previously proposed an estimation method for home dampness using occupants self-reported answers to questions about visible vapor condensation, visible mould growth during winter.

Allergic symptoms are closely related to indoor allergens, such as airborne particulate matter, fungi, and house dust mite. This paper introduces a central air-conditioning system integrated with an electrical dust collector developed as a countermeasure against allergy. Here, it was demonstrated that this air-cleaning system can remove fine particles of PM2.5. Objectively, this study aims to elucidate the relationship between indoor allergens and occupants’ allergic symptoms.

There is no doubt that odor is also an important factor to evaluate indoor air quality. Since the olfactory system was proven to be closely related to the limbic structures which support emotion, long-term memory and motivation, the psychological and the physiological effects of the essential oils have been widely researched in various fields. The odor environment formed by essential oils is popularly used in commercial facilities to make customers have special mood.