Estimating occupant satisfaction of HVAC system noise using quality assessment index

Abstract

Noise may be defined as any unwanted sound. Sound becomes noise when it is too loud, unexpected, uncontrolled, happens at the wrong time, contains unwanted pure tones or unpleasant. In addition to being annoying, loud noise can cause hearing loss, and, depending on other factors, can affect stress level, sleep patterns and heart rate. The primary object for determining subjective estimations of loudness is to present sounds to a sample of listeners under controlled conditions. In heating, ventilation and air conditioning (HVAC) systems only the ventilation fan industry (e.g., bathroom exhaust and sidewall propeller fans) uses loudness ratings. In order to find satisfaction, percent of exposure to noise is the valuable issue for the personnel who are working in these areas. The room criterion (RC) method has been defined by ANSI standard S12.2, which is based on measured levels of in HVAC systems noise in spaces and is used primarily as a diagnostic tool. The RC method consists of a family of criteria curves and a rating procedure. RC measures background noise in the building over the frequency range of 16-4000 Hz. This rating system requires determination of the mid-frequency average level and determining the perceived balance between high-frequency (HF) sound and low-frequency (LF) sound. The arithmetic average of the sound levels in the 500, 1000 and 2000 Hz octave bands is 44.6 dB; therefore, the RC 45 curve is selected as the reference for spectrum quality evaluation. The spectral deviation factors in the LF, medium-frequency sound and HF regions are 2.9, 7.5 and -2.3, respectively, giving a Quality Assessment Index (QAI) of 9.8. This concludes the QAI is useful in estimating an occupant's probable reaction when the system design does not produce optimum sound quality. Thus, a QAI between 5 and 10 dB represents a marginal situation in which acceptance by an occupant is questionable. However, when sound pressure levels in the 16 or 31.5 Hz octave bands exceed 65 dB, vibration in lightweight office construction is possible.

HVAC maintainability risks in healthcare facilities: a design optimization perspective

“…After reviewing similar studies (Albuainain et al, 2021;Zhang et al, 2018), the authors observed that occupants might be oblivious to maintenance issues in a facility. Besides, certain studies have investigated building performance evaluation and postoccupancy evaluation, which addressed HVAC systems in health-care facilities (Brambilla and Capolongo, 2019;Dilrukshi et al, 2014;Forouharmajd et al, 2012). However, these studies are limited and mainly focus on certain HVAC performance elements such as noise.…”

Integrated Value Engineering and Life Cycle Cost Modeling for HVAC System Selection

“…The influence of the HVAC system is vital, because it can contribute to reducing the energy consumption of a building and preserving appropriate indoor air quality [14]. In addition, the important criteria of choosing an HVAC system have to be considered, such as a low noise level in the building [15]. Furthermore, the ASHRAE standards give importance to the criterion of durability.…”

“…Heating options based on heat pumps Carrier [41] C5: Sound rating level System noise Farhad et al [15] C6: Air replenishment Use of fresh air in HVAC system ASHRAE standard 62.1 [42] In addition to criteria related to evaluating HVAC quality, according to previous studies, other criteria in the HVAC selection process are related to aesthetics, buildability, sustainability, and durability [16,17]. Eight HVAC selection criteria associated with system quality are described in Table 5.…”

“…Coefficient of performance, regulation performance, multi-purpose application, frosting, noise, life span, environmental protection, ease of use, space occupied, ease of construction, maintenance Liu and Zhao [68] Energy, user satisfaction, environment Avgelis and Papadopoulos [69] Energy efficiency ratio SASO 2663, 2874 [34,35] Air volume of system Centralized place for air diffuser Supply air diffuser sizing and location, crown power air-conditioning site [40] Heating conditioning in system Carrier, residential products, heat pumps (heat pumps vs. air-conditioners) [41] Sound rating level Farhad et al [15] Air replenishment ASHRAE Standard 62.1 [42] Aesthetics of system Ihsan [43] Measure dimensions, weights of HVAC units Measure ease of installation or construction…”

Electromagnetic vibration noise analysis of transformer windings and core

“…The unpleasant sound or noise is a factor that influences noise pollution (e.g., the noise produced by airplanes, cars, industrial process machinery, and sound systems), and therefore, devices like transformers can affect human beings [1,2]. In electrical transformers, noise can be caused by different physical effects, such as the pile-up of magnetic sheets that form the core, the winding, and the air forced cooling systems [3,4], which combined may provoke really high levels of noise that would exceed the limits established by national and international standards.…”