Ventilation in Residential Buildings - Modelling and on site Experimentation

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Publications

The influence of ventilation systems on domestic gas appliances: an experimental study

Publication . Pinto, Manuel; Viegas, João

Ventilation systems play an important role in the energy consumption of heating and cooling, defining hygrothermal conditions and air quality of dwellings. Among other functions, they are absolutely necessary to ensure oxygen levels needed for household combustion appliances. In Portugal in multifamily housing and with natural ventilation systems, installing a mechanical exhaust fan in every kitchen (decentralized ventilation) is common. In this paper, the impact of such a device is evaluated regarding the performance of a water heating appliance for heating the indoor environment or for domestic hot water (B-type gas appliance usually installed in the kitchen). The combination of natural or mechanical ventilation in the kitchen with the natural exhaust of the gas appliance’s combustion products were tested as well as the evaluation of critical conditions that lead to stopping the gas appliance safely or to reversing the combustion products in the respective exhaust duct. One of the main conclusions to be drawn is that in the case of mechanical exhaust in the kitchen simultaneously with the natural exhaust of the gas appliance’s combustion products, the kitchen’s exterior air inlet is a key device for ensuring proper exhaust of combustion products. In extreme situations, reduced air intake by other means or high extraction flows, they can prevent safely stopping the appliance or even reversing the flow of the combustion products. For this purpose, the maximum flow of mechanical exhaust should also be limited.

2013Journal article

Open access

Air permeability measurements of dwellings and building components in Portugal

Publication . Pinto, Manuel; Viegas, João; Freitas, Vasco

Ventilation represents a significant part of heat loss in winter, leading to the need to minimize airflow. However, it is absolutely necessary to ensure indoor air quality and the safety of the users and to control the risk of condensation. Ventilation is responsible on average for 30%e40% of energy consumption in air conditioning in Western European buildings. There is great variability in air change rates (ACH [h 1]) from country to country and the minimum value takes into account comfort, sensory and hygrothermal criteria. In Portugal improvements have been made in the air permeability of window frames, but despite the improvements also made in installing mechanical extraction ventilation devices in kitchens and toilets, these often do not guarantee the minimum number of air change rates required. Air permeability tests were recently carried out in five flats with identical construction characteristics, in the same building, with the aim of characterizing the air permeability of buildings and components, in Portugal. These data are particularly useful for improving the design of building components (e.g., windows and roller shutter boxes) and to perform simulations with reliable data.

2011-12Journal article

Open access

Residential Hybrid Ventilation Systems in Portugal:Experimental Characterization

Publication . Pinto, Manuel; Freitas, Vasco; Viegas, João; Matias, Luís

Due to the variation in natural factors, such as wind speed and the stack effect, natural ventilation systems are unlikely to provide permanent ideal ventilation rates. As such, this paper will characterize the performance of hybrid ventilation systems that are a possible solution to this drawback. This project presents the experimental study characterizing the hybrid ventilation system in a 100- apartment residential complex in the Porto area. The results of the measurements of temperature, humidity, flow rates in ducts, ACH by the PFT technique and weather conditions taken in seven flats are presented.

2006-06-04Journal article

Open access

The influence of ventilation in the work of domestic combustion appliances

Publication . Viegas, João; Pinto, Armando; Pinto, Manuel

In dwellings with collective ventilation systems users often install mechanical exhaust hoods in order to improve the exhaust flow rate. In this research the impact of such devices on the work of the gas water-heater appliance (usually installed in the kitchen) is assessed. Field testing was carried out in order to evaluate the performance of natural ventilation systems in a multi-storey building and its adequacy to provide conditions for the work of the gas waterheater. The combination of mechanical ventilation in hoods and natural exhaust of combustion products of gas water-heater was also tested and critical conditions that lead to the safety stop of the gas water-heater were evaluated. A computer simulation program was used to predict the occurrence of safety problems in the work of the gas water-heater with different mechanical exhaust rates and two different air permeability of the building envelope. It is shown that it is possible to reduce negative impact of mechanical devices increasing the envelope air permeability, but this action will largely increase building heat loss.

2007-06-13Journal article

Open access