Implication of Infiltration on Building Energy Demand - a Review of Verification Methods (original) (raw)
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Towards Development and Validation of a Simplified Infiltration Model for Commercial Buildings
2020
As building envelopes continue to become more thermally insulated, the impact of exfiltration/infiltration on space heating demand will become increasingly significant. Heat transfer through opaque and transparent envelope components is well-understood and characterized in building performance simulation (BPS); however, simple constant flow assumptions are often used for modelling air infiltration which can result in substantial inaccuracies in estimated performance. A detailed building thermal and air flow network model was developed as a case study to examine the sensitivity of envelope leakage site distribution to annual space heating energy. Additionally the model was used to determine if this sensitivity diminishes as a building is pressurized. Results of the case study indicate that distribution of leakage area varies annual energy estimates and average infiltration by ±3% and ±10%, respectively, when unpressurized. Pressurization was found to significantly increase sensitivit...
Energies
Airtightness is nowadays one of the physical parameters which determine overall building energy performance. In a wide range of states, the upper limit for air change rate at a Pa (na), air permeability rate at a Pa (qa), or specific leakage rate at a Pa (wa) is determined by the formal regulations. It should be highlighted that airtightness requirements are mainly the same around the world, disregarding any site and climatic conditions. The main goal of the presented work was to reveal the effect of individual location and surrounding infiltration rate and heat demand. The analyses were done using numerical techniques and computational models of the three buildings developed and calibrated based on the blower door test results. The compared buildings characterize by a similar geometry but differ in the air change rate at 50 Pa (n50). Analyses done for different locations and levels of sheltering by surrounding elements allow the determination of the real effect of local conditions....
Transstellar journal, 2018
Improving the energy and thermal performances of buildings involves studying all the internal and external factors that can affect them. These factors include air infiltration that can occur through the building envelope. In order to meet the requirements of their thermal regulations, the measurement of infiltration become a common practice in some European and North American countries. Although this practice is still very rare in Morocco even not applied. In order to estimate the impact of air infiltration on the energy consumption of the Moroccan residential sector, we have carried out measurements using pressurization by blower door in four houses located in Casablanca with different standings and characteristics. The dynamic modelling of houses with measured leakage rates allow us to quantify the thermal losses due to infiltration and the corresponding energy impact. The dynamic modelling results show that the interior temperatures of the four houses are negatively impacted by up to 3.5 degrees and that the additional energy cost reaches up to 26% of the winter electricity consumption.
Effect of Air Infiltration Rate on Energy Consumption of a Residential Building in Bebena, Thimphu
Bhutan Journal of Research and Development
Energy consumption in buildings has been a major concern in the present construction field and the parameters that affect its performance should be carefully studied. Building airtightness is an important contributing factor to the energy consumption of a building. The measurement of air infiltration is widely practiced in some countries of Europe and North America. However, this practice is still rare and uncommon in Bhutan. At present, traditional dwellings of Bhutan have been found to be very leaky as compared to the modern Reinforced concrete structure (RCC) buildings mainly due to construction materials and techniques. The paper consists of air infiltration test carried out by the blower door method at a residential building in Bebena, Thimphu. The test has been followed by a series of data collection and interpretation of the readings obtained on site. The result obtained was air movement of 11.9-h through the building envelope which was satisfactory as in the case of Bhutan b...
Calculating infiltration: Implications for a construction quality standard
Extensive work in infiltration measurement and modeling has led to a simple method to calculate the leakage area of a house regardless of design or weather conditions. The leakage area, in turn, is used in the LBL infiltration model to calculate infiltration for any weather condition. This method, which uses fan pressurization to measure the leakage area, has been used in a survey of over 300 houses located throughout North America. The results of that survey are presented and it is suggested that the present capability in infiltration modeling offers an excellent framework for an air leakage standard for residential building. Examples of the interpretation of such a standard are described based on the ventilation rates adopted in ASHRAE Standard 62-1981. The results of the interpretations illustrate differences in structural requirements that will occur when such a standard is applied to several ventilation system designs.
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The air infiltration of a building, which fundamentally depends on its airtightness, can be a significant contributor to its heat loss. It can also be affected by other factors such as external terrain, leakage distribution, sheltering factor and environmental conditions. The infiltration rate of a detached UK house was monitored for 2 months in early 2018 using constant concentration and decay tracer gas methods under various temperature and wind conditions. Different temperature differences across the building envelope were achieved by heating up the indoor air with the assistance of fan heaters. Various wind conditions were covered by carrying out tracer gas tests continuously over a few days during which different wind conditions were captured. The external pressure distribution on each side of the building envelope was also monitored using differential pressure transducers. The impact of the wind on the external pressure distribution was investigated in order to understand how ...
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A novel method for determining air infiltration for mechanically ventilated buildings is presented in this paper. It consists of a model that uses size-resolved particle concentrations of the outdoor, filtered supply, and exhaust air as input. Based on these continuously measured concentrations, the infiltration rate can be inferred by fitting the experimentally obtained indoor concentrations with theoretically calculated values. The approach was validated by continuous long-term field measurements made over a four-month period. The results show that infiltration rates could be reliably estimated using this method and that the calculated infiltration rates were clearly dependent on the wind speed.
Infiltration Rate (air leakage) in modern Urban Jordanian Buildings in Amman
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Simulation of Air Infiltration of Australian Housing and its Impact on Energy Consumption
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To evaluate potential air infiltration model improvement for AccuRate, a benchmark housing energy star rating tool widely used in Australia, three different infiltration models have been developed. This paper presents a comparison of the calculated air infiltration rates and building energy performance using the three models. Case studies for eight houses in Melbourne, Australia, show there are up to 37% and 13% differences in the calculated average infiltration rates and modelled heating and cooling energy demand respectively between these three models.