Airtightness improvement of structures to improve indoor air quality

The aim of improving air tightness of structures is to prevent the uncontrolled air leakages through structures. Built environments contain microbes, particulate and gaseous impurities but removing them is not always necessary. For example, an ageing building envelope commonly contains microbial impurities even when there is no obvious moisture damage. Air leaks convey impurities to indoors where they can lead to poor indoor air quality and associated health problems. Air leaks have also negative impact to energy efficiency and living comfort.

Impact of a photocatalytic oxidation layer covering the interior surfaces of a real test room: volatile organic compound mineralisation, risk assessment of by-product and nanoparticle emissions.

Many studies about photocatalytic oxidation (PCO) have been carried out in laboratories. They use an inert test chamber with ideal indoor conditions: a low volume, a controlled temperature and humidity, and a constant injection of one to five specific gases. The principal aim of this study was to implement, in a real test room (TR) of an experimental house, a titanium dioxide (TiO2) layer to quantify its efficiency.

National Survey on Ventilation Systems and the Health of Occupants in Japanese Homes

The indoor environmental quality and health of occupants in approximately 5000 dwellings were investigated by questionnaire covering the whole of Japan. The purpose of this survey was to clarify the association between indoor air quality and adverse health effects and to study effective ways of keeping indoor air clean using mechanical ventilation. Questionnaires were distributed to 7812 occupants living in mechanically ventilated houses across 47 Prefectures in Japan in February 2012 of which 5265 occupants replied.

Natural Ventilation Potential in Portuguese Residential Buildings under Winter Conditions – An Opportunity for Hybrid Ventilation

This paper presents a study of the potential for the use of natural ventilation systems in Portuguese multi-family residential buildings under winter climatic conditions. The behaviour of various natural ventilation systems is tested in a standard residential dwelling, using the TRNSYS 15 and COMIS 3.1 software programs. This study leads to the conclusion that the use of hybrid ventilation systems can save a considerable amount of the energy normally spent on continuously operating mechanical ventilation systems.

Diffuse Ceiling Ventilation - A Review

As a novel air distribution system, diffuse ceiling ventilation combines the suspended acoustic ceiling with ventilation supply. Due to the low-impulse supply from the large ceiling area, the system does not generate draught when supplying cold air. However, heat sources play an important role on thermal comfort in the occupant zone. Another characteristic of this system is its lower pressure drop compared with conventional ventilation systems, which reduces the noise problem and, at the same time, the energy consumption of the fan can be reduced.

Robust Design for high workers’ performance and low absenteeism – An alternative approach

Rehva Guide No 6 – Indoor Climate and Productivity in Offices - states as its main purpose to establish quantitative relationships of indoor environmental aspects with performance and sickness absenteeism. The following relationships were established: temperature with performance, ventilation with performance, perceived indoor air quality with performance and ventilation with sickness absenteeism.

A coupled summer thermal comfort and indoor air quality model of urban high-rise housing

The synergistic effects between summertime ventilation behaviour, indoor temperature and air pollutant concentration in relation to energy retrofit and climate change have been under-investigated to date. This paper explores such interactions in a social housing setting. The case study flat is located on a mid-floor of a high-rise council tower block in central London. Dwellings of this type are likely to be occupied by vulnerable individuals (elderly people or people suffering from ill health or mobility impairment).

Life-cycle cost simulation of in-duct ultraviolet germicidal irradiation systems

Ultraviolet Germicidal Irradiation (UVGI) systems use 254 nm UVC radiation to inactivate microorganisms in the air and on surfaces. In-duct UVGI systems are installed in air-handling units or air distribution systems to inactivate microorganisms “on the fly” and on surfaces.  The literature contains few investigations of the economic performance of UVGI. This study presents a simulation-based life-cycle cost analysis of in-duct UVGI in a hypothetical office building served by VAV systems.

Annual simulation of in-duct ultraviolet germicidal irradiation system performance

In-duct ultraviolet germicidal irradiation (UVGI) systems treat moving air streams in heating, ventilation, and air-conditioning (HVAC) systems to inactivate airborne microorganisms. UVGI system performance depends on air temperature, velocity, cumulative operating time, variations in exposure time and other factors. Annual simulations of UVGI efficiency and space concentration that accounted for these effects were performed for a hypothetical building served by a VAV system.

Analysis on the well-mixing assumptions used in multizone airflow network models

The well-mixing assumptions, uniform distributions of air temperatures and contaminant concentrations and neglect of air momentum effects in a zone, used in multizone airflow network models could cause errors in some cases. Through dimensional analysis of the published data from the literature, this study has found correlation between the errors and mixing levels. Our study concluded that the assumption of uniform air temperatures is not appropriate if the  vertical non-dimensional temperature gradient is higher than 0.03.