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M. Liˇ canin et al.
1 Introduction
Heated Ventilated Air Conditioning Units (HVAC) are important parts of modern
buildings, especially those that have community purposes (offices buildings, supermarkets, shopping malls, hospitals, etc.). Very often, these types of systems are
positioned on the rooftops of buildings, where there is enough physical space. To
perform with optimal working parameters, air intake and exhausts of the unite should
have enough airflow [1]. HVAC (Chiller) units often move a massive amount of air
around them, producing a significant amount of noise. This becomes a problem,
which is not easy to solve using classical acoustic enclosures, due to the fact that air
supply needs to be provided. Generated noise becomes especially prominent during
the hot summer days, where people in residential areas and office buildings tend to
open windows and balconies for fresh air. Noise problem then becomes one of the
biggest environmental disturbances.
Engineering challenge when performing the noise control of the HVAC systems
is to provide the proper noise attenuation [2, 3] while at the same time allow the
device sufficient airflow. This paper exploits the possibility of using the special type
of segmented barrier as a solution to the noise problem. It also follows the most
important steps of the project that was successfully realized at the central office
building of one international bank in Belgrade. After identifying the problem at the
site location, a series of simulations of the segmented barrier has been performed in
COMSOL. Based on the simulation and in situ measurements, this type of barrier has
been designed and implemented. In order to visualize the problem, a 1:1 3D model
using Sketchup software has been built. After the construction and panel mounting is
performed, measurements have been retaken, and results of the practical application
observed.
2 Noise Evaluation
Measurements have been taken at positions presented in Fig. 1. Three measurement
positions have been chosen at 1 m distance from the each of the noise sources (1, 2,
and 3 on Fig. 1), while three positions were chosen on the noise path near the affected
building (4, 5, 6 on Fig. 1). Three chillers are positioned on the rooftop of the support
technical facility next to the bank office building. Noise is generated towards another
office building across the small street, which is considered as a noise receiver.
Measurement interval has been set to 5 min, and measurements were taken three
times at each chosen position. HVAC units can be set in different operation modes and
under different output loads. For the measurement conditions, all three chillers have
been set in high load regime without working regime change during measurements.
This allowed that the source can be considered as a stationary noise source. Another
way of performing measurements would be to use longer intervals, which will cover
all of the working regimes of the noise source [4]. Noise levels of measurement
M. Liˇ canin et al.
1 Introduction
Heated Ventilated Air Conditioning Units (HVAC) are important parts of modern
buildings, especially those that have community purposes (offices buildings, supermarkets, shopping malls, hospitals, etc.). Very often, these types of systems are
positioned on the rooftops of buildings, where there is enough physical space. To
perform with optimal working parameters, air intake and exhausts of the unite should
have enough airflow [1]. HVAC (Chiller) units often move a massive amount of air
around them, producing a significant amount of noise. This becomes a problem,
which is not easy to solve using classical acoustic enclosures, due to the fact that air
supply needs to be provided. Generated noise becomes especially prominent during
the hot summer days, where people in residential areas and office buildings tend to
open windows and balconies for fresh air. Noise problem then becomes one of the
biggest environmental disturbances.
Engineering challenge when performing the noise control of the HVAC systems
is to provide the proper noise attenuation [2, 3] while at the same time allow the
device sufficient airflow. This paper exploits the possibility of using the special type
of segmented barrier as a solution to the noise problem. It also follows the most
important steps of the project that was successfully realized at the central office
building of one international bank in Belgrade. After identifying the problem at the
site location, a series of simulations of the segmented barrier has been performed in
COMSOL. Based on the simulation and in situ measurements, this type of barrier has
been designed and implemented. In order to visualize the problem, a 1:1 3D model
using Sketchup software has been built. After the construction and panel mounting is
performed, measurements have been retaken, and results of the practical application
observed.
2 Noise Evaluation
Measurements have been taken at positions presented in Fig. 1. Three measurement
positions have been chosen at 1 m distance from the each of the noise sources (1, 2,
and 3 on Fig. 1), while three positions were chosen on the noise path near the affected
building (4, 5, 6 on Fig. 1). Three chillers are positioned on the rooftop of the support
technical facility next to the bank office building. Noise is generated towards another
office building across the small street, which is considered as a noise receiver.
Measurement interval has been set to 5 min, and measurements were taken three
times at each chosen position. HVAC units can be set in different operation modes and
under different output loads. For the measurement conditions, all three chillers have
been set in high load regime without working regime change during measurements.
This allowed that the source can be considered as a stationary noise source. Another
way of performing measurements would be to use longer intervals, which will cover
all of the working regimes of the noise source [4]. Noise levels of measurement