Ventilation behavior in residential buildings with mechanical ventilation systems across different climate zones in China

Energy-saving ventilation systems are designed to improve the energy efficiency of buildings. Low energy efficiency in buildings poses a considerable problem that needs to be addressed. Mechanical ventilation with heat recovery has gained increased popularity in recent years. Mechanical ventilation has numerous advantages, including easy adjustment and control, high indoor air quality and elimination of indoor pollutants. Mixing ventilation is the most popular type of mechanical ventilation, in particular in residential buildings. Unsteady ventilation is a type of mixing ventilation that involves stronger mixing effects and smaller vertical temperature gradients to improve indoor air quality (IAQ) and minimize energy consumption. This study examines the possibility of controlling and modifying Coanda effect hysteresis (CEH) to generate unsteady flow and simulate the conditions of unsteady mixing ventilation. The experiment was performed on a self-designed test bench at the University of Warmia and Mazury in Olsztyn. It demonstrated that an auxiliary nozzle can be applied at the diffuser outlet to control CEH and the angles at which the air jet becomes attached to and separated from the flat plate positioned directly behind the nozzle. The study proposes an innovative mixing ventilation system that relies on CEH. The potential of the discussed concept has not been recognized or deployed in practice to date. This is the first study to confirm that an auxiliary nozzle by the diffuser outlet can be operated in both injection and suction mode to control CEH. In the future, the results can be used to design a new type of nozzles for unsteady ventilation systems that are based on CEH control.

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Investigation of Ventilation Behaviors in Mechanically Ventilated Residential Buildings in China

E3S Web of Conferences ◽

10.1051/e3sconf/201911106048 ◽

2019 ◽

Vol 111 ◽

pp. 06048

Author(s):

Yue Qi ◽

Junjie Liu ◽

Xilei Dai ◽

Lei Zhao ◽

Dayi Lai ◽

...

Keyword(s):

Mechanical Ventilation ◽

Energy Efficient ◽

Natural Ventilation ◽

Residential Buildings ◽

Ventilation System ◽

Outdoor Air ◽

Climate Zones ◽

Mechanically Ventilated ◽

Ventilation Duration ◽

Site Monitoring

Mechanical ventilation system provides a more reliable, controllable, and comfortable way of ventilation than natural ventilation through an opened window. However, the operation of mechanical ventilation system cost energy. This study investigated the usage of natural and mechanical ventilation in 46 apartments in ten cities across five different climate zones in China by on-site monitoring and questionnaire survey. On average, the daily natural and mechanical ventilation durations were 11 hours and 7.2 hours, respectively. Large differences existed among climate regions and seasons. From north to south, as the climate became warmer, the usage of natural ventilation increased. From seasonal perspectives, natural ventilation duration was the longest in summer and the shortest in winter. The trend of mechanical ventilation usage was opposite to that of natural ventilation. Generally, as the outdoor air temperature increased, the duration of natural ventilation increased and the duration of mechanical ventilation decreased. This study proposed an outline to use thermal comfort, health, and energy saving as three motivations to analyze ventilation behaviors. Based on the obtained results, suggestions were made for achieving healthy, thermally comfortable, and energy efficient ventilation in residential buildings.

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Controlled mechanical ventilation systems in residential buildings: Primary energy balances and financial issues

Journal of Building Engineering ◽

10.1016/j.jobe.2017.04.010 ◽

2017 ◽

Vol 11 ◽

pp. 96-107 ◽

Cited By ~ 7

Author(s):

G. Evola ◽

A. Gagliano ◽

L. Marletta ◽

F. Nocera

Keyword(s):

Mechanical Ventilation ◽

Residential Buildings ◽

Primary Energy ◽

Controlled Mechanical Ventilation ◽

Energy Balances ◽

Financial Issues ◽

Ventilation Systems

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APPLICABILITY OF VENTILATION SYSTEMS FOR REDUCING THE INDOOR RADON CONCENTRATION

Radiation Protection Dosimetry ◽

10.1093/rpd/ncaa148 ◽

2020 ◽

Vol 191 (2) ◽

pp. 202-208

Author(s):

Martin Jiránek ◽

Veronika Kačmaříková

Keyword(s):

Mechanical Ventilation ◽

Energy Consumption ◽

Radon Concentration ◽

Residential Buildings ◽

Indoor Radon ◽

Ventilation System ◽

Supply Rate ◽

Indoor Radon Concentration ◽

Building Ventilation ◽

Ventilation Systems

Abstract An analysis is presented of the ability of balanced mechanical ventilation systems to reduce the radon concentration in residential buildings efficiently. The analysis takes into account the following parameters: radon supply rate into the building, ventilation intensity, required indoor radon concentration and energy consumption. It is shown that the applicability of ventilation systems is limited mainly by energy consumption. Ventilation systems can be considered energetically acceptable if the ventilation intensity does not exceed 0.6 h−1, i.e. radon supply rate should not exceed 60 Bq/m3h for a required indoor radon concentration of 100 Bq/m3. Energy consumption can be significantly reduced by operating the ventilation system in a cyclic mode. Simulating the behavior of ventilation systems in time has been found as a useful tool for their design. In order to express by one parameter energy consumption and radon reduction, a completely new quantity—the ‘radon-related energy need’ has been proposed.

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Operating behavior and corresponding performance of mechanical ventilation systems in Chinese residential buildings

Building and Environment ◽

10.1016/j.buildenv.2019.106600 ◽

2020 ◽

Vol 170 ◽

pp. 106600 ◽

Cited By ~ 1

Author(s):

Lei Zhao ◽

Junjie Liu

Keyword(s):

Mechanical Ventilation ◽

Residential Buildings ◽

Ventilation Systems

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Proposing Alternative Solutions to Enhance Natural Ventilation Rates in Residential Buildings in the Cfa Climate Zone of Rasht

Sustainability ◽

10.3390/su13020679 ◽

2021 ◽

Vol 13 (2) ◽

pp. 679

Author(s):

Roya Aeinehvand ◽

Amiraslan Darvish ◽

Abdollah Baghaei Daemei ◽

Shima Barati ◽

Asma Jamali ◽

...

Keyword(s):

Natural Ventilation ◽

Residential Buildings ◽

Residential Building ◽

Ventilation Rate ◽

Humid Climate ◽

The Sustainable Development ◽

Passive Strategies ◽

Development Goals ◽

Ventilation Rates ◽

Ventilation Systems

Today, renewable resources and the crucial role of passive strategies in energy efficiency in the building sector toward the sustainable development goals are more indispensable than ever. Natural ventilation has traditionally been considered as one of the most fundamental techniques to decrease energy usage by building dwellers and designers. The main purpose of the present study is to enhance the natural ventilation rates in an existing six-story residential building situated in the humid climate of Rasht during the summertime. On this basis, two types of ventilation systems, the Double-Skin Facade Twin Face System (DSF-TFS) and Single-Sided Wind Tower (SSWT), were simulated through DesignBuilder version 4.5. Then, two types of additional ventilation systems were proposed in order to accelerate the airflow, including four-sided as well as multi-opening wind towers. The wind foldable directions were at about 45 degrees (northwest to southeast). The simulation results show that SSWT could have a better performance than the aforementioned systems by about 38%. Therefore, the multi-opening system was able to enhance the ventilation rate by approximately 10% during the summertime.

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The impact of mechanical ventilation operation strategies on indoor CO2 concentration and air exchange rates in residential buildings

Indoor and Built Environment ◽

10.1177/1420326x20960767 ◽

2020 ◽

pp. 1420326X2096076

Author(s):

Pedro F. Pereira ◽

Nuno M. M. Ramos

Keyword(s):

Mechanical Ventilation ◽

Air Quality ◽

Exchange Rates ◽

Indoor Air Quality ◽

Indoor Air ◽

Residential Buildings ◽

Ventilation Strategy ◽

The Impact ◽

Mechanical Extraction ◽

Air Exchange

In Portugal, residential buildings commonly have their ventilation strategy changed after commissioning. This occurs due to the building managers' willingness to reduce shared costs with the electricity needed for fan operation. However, this option is not technically supported, and the effects of such a strategy on indoor air quality-related to human pollutants are yet to be quantified. CO2 was monitored in 15 bedrooms and air exchange rates were calculated for each room. The air exchange rate values ranged from 0.18 to 0.53 h−1 when mechanical extraction ventilation was off, and from 0.45 to 0.90 h−1 when mechanical extraction ventilation was on, which represents an average increase of 119%. With the current intermittent ventilation strategy, all rooms remain above 1500 ppm for a given percentage of time, and 12 rooms presenting CO2 concentrations above 2000 ppm. Simulations of theoretical CO2 concentrations, for a non-interrupted mechanical ventilation strategy show that no rooms would accumulate CO2 concentrations above 2000 ppm, and only 25% would present CO2 concentrations above 1500 ppm. Pearson correlations between the monitored CO2 and human and spatial factors identified two relevant parameters. Those parameters correspond to ratios between CO2 generation and floor area ([Formula: see text]), and airflow with CO2 generation ([Formula: see text]). The proposed ratios could be used as ways to optimise ventilation costs and indoor air quality.

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