Decentralized mechanical ventilation systems had a sustainable growth in the past ten years in order to guarantee air exchange in highly airtight renovated residential buildings. Smart control strategies could provide a solution to the tradeoff between energy efficiency, hygrothermal comfort and indoor air quality. In this paper, a novel fuzzy demand controlled ventilation strategy is proposed, using

(2020). Integrating IAQ control strategies to reduce the risk of asymptomatic SARS CoV-2 infections in classrooms and open plan offices. Science and Technology for the Built Environment: Vol. 26, No. 8, pp. 1013-1018.

(2020). Investigating the impact of filters on long-term particle concentration measurements in residences (RP-1649) Science and Technology for the Built Environment: Vol. 26, No. 8, pp. 1037-1047.

It is widely acknowledged that demand response must play an increasingly important role in future electricity markets. This is as much due to increasing demand for air-conditioning as it is due to the changing sources of generation. In the National Electricity Market (NEM) in Australia, for just 3% of the year demand increases by 20%, or the equivalent of the generation from the two largest coal fired

This paper presents a near-optimal control algorithm for minimizing energy costs in hybrid cooling plants in response to cooling loads. The approach is based upon an approximate solution to the partial differential equations involved in minimizing the cost of energy consumed by the plant with respect to two control variables: cooling tower airflow and condenser water flow. The parameters of the algorithm

Building automation system uses several networks of sensors for continuous monitoring of building control systems for energy-efficient operation. Physical sensors are costly and need frequent calibration. The accurate measurement of supply air temperature from the air handling units (AHUs) has an important effect on the control of cooling coil, supply air temperature and supply airflow rate delivered

With the continuous promotion of urbanization, numerous large-scale public buildings appear in cities. Concerning the characteristics of large floor-area and high personnel-density, creating a thermally comfortable environment is significant to large-scale buildings. However, uneven thermal environment is usually detected in large-scale space, which shows that some areas are overcooled while some lack-cooling

Growing number of household refrigerators and freezers also increase the overall energy consumption and number of household refrigerators have grown nearly 3% per year. On the other hand, investigations showed that household refrigerators have a significant technical energy saving potential of up to 30-40%. In this study, a single-phase natural circulation loop is considered as a suction line heat

Systematic and random errors for working sensors in building systems can seriously affect the operation performance and have a significant negative impact on energy efficiency and indoor comfort. However, the traditional method for sensor calibration is very time-consuming and labor-intensive. Therefore, a virtual in-situ calibration (VIC) method was proposed based on Bayesian inference that can simultaneously

Motor-driven fan systems in air handling units (AHUs) account for 15.9% of the electricity consumption in commercial buildings. Currently electronically commutated motors (ECMs) have seen increasing applications to replace induction motors for energy savings. While efficiency models for motor-driven fan systems are essential for building energy management, there is no valid efficiency model for ECM

In this study, R404A and R452A refrigerants used in refrigeration systems were compared experimentally. The energy performance of the system was investigated for widely used evaporation temperatures (−5, 0, +5 °C) and condenser temperatures (25, 35, 45 °C). It was seen that COP was higher but power consumption of system was lower using R452A as a substitute for R404A. When R452A was used, COP was improved

Accurate performance measurements of equipment in the laboratory requires air mixing to reduce temperature and humidity measurement error. The National Bureau of Standards (NBS), now known as National Institute of Standards and Technology (NIST) conducted in-depth experimental research on the static air mixing devices in the late 1960s, which remains the most comprehensive work in this area. Today

Thermal adaptation plays crucial role in energy efficient operation of buildings without compromising with human thermal comfort. Elevated air velocity is commonly desired to restore comfort requirements at higher temperatures especially in NV and MM buildings located in tropical countries like India. This paper is the systematic field study comprising a total of 4872 responses (1874 from NV buildings

Ventilation systems are necessary to ensure a good indoor air quality, especially in buildings characterized by high energy performance. An all-air system could be more flexible than radiant systems that need to be combined with other systems to provide fresh air and control latent loads. In this work, a multi-zone all-air system has been compared with a radiant floor integrated with mechanical controlled

An experimental test rig is utilized to measure the effects of the flow configuration and particularly the rib geometry, on the thermal performances of solar air heaters. Since the heat transfer rate within the entry length is relatively high, the implementation of the ribs needs to be justified. Computational fluid dynamics simulations are also conducted to support the experiments and to provide detailed

In order to investigate the impact of water quality on fouling process of enhanced tubes, two continuous fouling tests on eight enhanced tubes (with different internal and external tube geometries) and one plain tube (with a plain inside surface and an enhanced outside surface) were carried out in duration of 98 days, using cooling water with medium and low fouling potential respectively at a water

In current design practice, chillers and pumps are often oversized due to conservative consideration of uncertainties using safety factors to avoid the risk of undersizing, which often results in significant energy waste in operation. In recent years, probabilistic optimal design methods have been proposed for the components of cooling systems, enabling risk-based decision-making rather than sizing

A novel dataset based on satellite observations of aircraft positions was utilized to estimate normal accelerations of commercial aircraft during climb and descent legs. Further, these accelerations are used to simulate the effects on exposure to expiratory airborne contaminant inside commercial aircraft cabins. Compared to previous studies, which reported exposures more than twice due to high aircraft

In this study, a detailed modeling applicable for membrane dehumidifying system is proposed. This system contains a membrane module, 2-stage vacuum pumps, a condenser, and a regulating valve. The proposed model does not need any prior setting of the vacuum level of the permeate side, and the predictive results are in line with the benchmark. It is found that the COP (coefficient of performance) is

Energy can be recovered from building exhaust via water vapor transport and heat transfer across gas permeation membranes, thereby reducing latent and sensible loads during both heating and cooling seasons. The process known as membrane-based energy recovery ventilation (ERV) has been commercialized by several HVAC manufacturers, but so far has mostly been offered in flat sheet membrane configurations

Part-load performance models for fans driven by electronically commutated motors in fan-powered terminal units were developed based on the analysis of data from 36 series and parallel units provided by four manufacturers. Fan motors ranged from 0.33 to 1 hp (249 to 746 W) and maximum external static pressures from 0.5 to 0.75 in. w.g. (125 to 188 Pa). Part-load performance was estimated from the intersection

With an equal mass, nanoparticles (NP) have a higher toxicity than particles with the same chemical composition but with larger surface area. However, the toxicological knowledge concerning NP is still insufficient to establish limit values of exposure. To seek the lowest exposure level, filtration is a simple and effective way to capture particles, including NP. According to ANSI/ASHRAE 52.2 standard

The air-source heat pump (ASHP) is a popular system that does not see much use in cold-climates despite its high potential in low carbon footprint. This study was designed to evaluate the techno-economic feasibility of its application to single-detached homes in Canada. First, a set of support vector regression (SVR) models was developed by a housing database for prediction of the exposed surface areas

Utilization of PCM-to-Air Heat Exchangers (PAHXs) in building free cooling applications has been reporting the insufficient cooling charging energy during the PCM solidification, which affects the overall system performance. This study reports the improvements in the cooling potential of the PAHX considering the climatic characteristics of the hot desert climate by taking the advantage of thermal radiation

A cooling tower (CT) model was built based on physical thermodynamics and heat and mass transfer principles using the effectiveness-NTU method for heat exchanger performance. The focus of the model was to use non-intrusive measurements and predict the exiting water temperature from the cooling tower given certain inputs. Compared with the existing models, the new model has two main advantages: (1)

This paper assesses the current level of the application of passive/natural and daylighting systems in the US by architects and engineers. Although an extensive list of publications about passive/natural and daylighting systems exists, there are very few studies addressing the degree of applying these systems in practice. This paper, through the application of a survey methodology, evaluates the level

In this study, the combined power and refrigeration cycles driven by low-grade thermal energy is evaluated. An organic Rankine cycle (ORC) and a vapor compression refrigeration cycle (VCRC) are linked for both power generation and cooling. Three different combined cycle configurations are considered in the analyses. These are a basic ORC-VCRC, a dual-fluid basic ORC-VCRC, and a dual-fluid ORC-VCRC

By coupling algorithmic optimization with parametric modelling and performance simulation, the building design process becomes a series of informed decision-making. Algorithmic optimization helps architects find high-performance design choices which balance complicated trade-offs among various performance objectives. Although algorithmic-optimization aided design is more competent than the traditional

In this study, three different diffusers (V profile perforated, flat anemostat type and pyramid anemostat type) have been designed in order to spread the air in shorter distance in empty cells used in central air handling units. The pressure drop caused by these diffusers has been investigated experimentally. The diffusers are mounted at the center of the fan outlet section, up or down the center (the

In-duct ultraviolet germicidal irradiation (UVGI) systems are effective systems that are used in disinfection of pathogenic particles transported by air that moving through the ventilation systems. Proper design of these systems is quite important for energy consumption and disinfection performance. In this study, effect of four different lamp arrays within a square cross-section ventilation duct on

An automotive air conditioning and heat pump (AAC/AHP) system employing refrigerants R134a and R1234yf was developed and tested in cooling and heating operation modes under broad ranges of compressor speed and air inlet temperature conditions. Using test results, various energetic and exergetic performance parameters of the system were evaluated and compared. The R1234yf system provided on average

The main objective of this study is to determine the optimum insulation thickness of residential buildings in Turkey, under the influence of cooling and heating loads by life cycle cost analysis (LCCA). 5-storey apartment building with an Area/Volume ratio (A/V) of 0.40 m−1 and 10-storey apartment building with an A/V ratio of 0.32 m−1 are taken as reference buildings. The annual energy needs are calculated

The aim of this study is to investigate dispersion and deposition characteristics of different particle diameters (0.5–5–10 μm) for a displacement ventilated and floor heated environment, experimentally and numerically. The experiments are performed in a reduced scale model with the operating parameters determined regarding to the similarity. Results are used to validate simulation outputs obtained

There are no ASHRAE/HVI standards for characterizing or specifying acceptable values of capture efficiency (CE) (i.e. percentage of cooking-contaminants captured/exhausted by a household rangehood). A test method, ASTM-E3087.18, was recently published describing a facility/procedure for attaining consistent CE measurements. This study presents the design, construction and operation of the first CE

Chillers consume considerable energy in building HVAC systems, and the optimal operation of chillers is essential for energy conservation in buildings. This article proposes a model-free optimal chiller loading (OCL) method for optimizing chiller operation. Unlike model-based OCL methods, the proposed method does not require accurate chiller performance models as a priori knowledge. The proposed method

Existing studies have treated variable refrigerant flow (VRF) control as a local control problem where control variables are determined using only local state information. This study investigates an integrated VRF control in which the VRF control actions are determined based on not only local information but also the dynamics of the room it serves. For this purpose, two artificial neural network simulation

The existing fault detection and diagnosis (FDD) model of chillers requires considerable normal and fault data. The acquisition of these data is time-consuming and expensive, and the model is only suitable for special units, which makes it difficult to popularize FDD technology in the operation and management of chillers. At present, a 120-ton chiller has only a small amount of normal and fault data

Combined district heating (DH) systems have at least one base load heat plant and several peak shaving heat sources, which can be installed in primary network or in the heating substations. This paper studies the combined DH system with peak shaving gas-fired boilers in heating substations, where the peak boilers can be connected to the heat exchangers with series or parallel mode. We analyze the thermal

Building energy estimation for the building sector under various scenarios are needed for building energy regulation and policy making. This often starts with representative baselines (either empirical baseline or modeled baseline). Commercial Buildings Energy Consumption Survey (CBECS) data is a widely used empirical baseline for U.S. commercial buildings, but none of the existing baseline model are

Public attention has been drawn to the commercial restaurant cooking emission since it can cause health and hygiene risks, reduction of the efficiency of the ventilation system, and even fire accidents. The attempt of including the Ultraviolet-C (UVC) lamps with Type I hood has the potential to reduce the grease deposition on the ductwork and pollution in the exhaust by oxidizing the emissions. A method

(2020). Flammable refrigerant safety. Science and Technology for the Built Environment: Vol. 26, Flammable Refrigerant Safety, pp. 587-587.

Sleep is essential for the body to recover from both the physical and psychological fatigue accruing throughout the day, and to restore energy to maintain bodily functions. Bedroom environmental quality is one of the key causes of sleep disturbance, so a better understanding of the associations of bedroom temperature and ventilation rate (using CO2 as the surrogate) with sleep quality is necessary

In recent years, severe and persistent winter haze has appeared more frequently due to coal-combustion heating for residential buildings in the winter in northern China. To solve the problem, the Chinese government proposes to replace coal-combustion heating with electricity-driven air-source heat-pump heating. In this article, the performance of an air-source heat pump was studied for suburban residential

Cooling water (CW) system with strong nonlinear characteristics is a critical component of central air conditioning systems. Further, variable flow control of CW pumps is a critical measure for achieving energy-saving operation of CW systems. Proportional–integral (PI) control algorithm is widely used in the variable flow control of CW systems, and fuzzy control algorithm also plays a significant role

The influence of three ventilation systems, namely, the displacement ventilation system, the stratum ventilation system, and the underfloor air distribution system, on human thermal comfort was investigated at different supply air temperatures. We compared the air velocity, CO2 concentration, temperature, human thermal comfort, and energy utilization coefficient of the three systems at a supply air

This paper presents the application of a multi-agent control methodology to large chiller plants. The approach, originally conceived to automate controller design and reduce engineering costs in building energy systems, consisted of a multi-agent simulation framework with distributed consensus-based optimization algorithms. To adapt the approach to this scenario, agents representing physical components

Particle filters are used in heating, ventilating, and air-conditioning (HVAC) systems to protect equipment and reduce exposure to airborne particles. Filtration standards such as ANSI/ASHRAE Standard 52.2 are used to evaluate filter performance in a laboratory setting. In this work, we examined the lab-tested performance of new filters with different nominal efficiencies as determined by ASHRAE Standard

This paper describes the development of a method that can be used to simulate in a laboratory the effects of air side fouling of condensers from split system air conditioners. The method includes a synthetic fouling agent that realistically mimics field fouling. The fouling agent was developed by considering the fouling materials and effects on heat transfer and air side pressure drop that were measured

Finite-element models were developed to predict the deformation of unreinforced spiral flat oval ducts when subjected to a range of positive/negative internal gauge pressures. The models included the effects of duct self-weight. Deflection predictions resulting from a linear analysis and a nonlinear analysis were contrasted. This study also compared finite-element model predictions to experimentally

HVAC filters are exposed to a diverse mixture of aerosols during their service life. Aerosol physiochemical properties can have a significant impact on the removal efficiency and loading behavior of a filter. New aerosol generation techniques are needed to age HVAC filters with particle size distributions (PSDs) representative of those found in outdoor (urban) and indoor environments. This study evaluated

A common form of particulate air filters is the pleated filter. The pressure drop and particle removal efficiency are the most important performance indicators of this filter. A computational fluid dynamics (CFD) tool was utilized to predict the pressure drop of a two-stage filter cartridge. In the CFD analysis, the flow through the porous medium was used as an indicator of the pressure drop in the

For measurements of unitary HVAC&R equipment and heat exchanger performance, tolerances on capacity measurements relative to the published ratings or mismatch in energy balances are limited to 5% as mentioned in AHRI standards (210/240, 340/360, and 365), ASHRAE 33 and 37, and in U.S. federal regulations. However, differences in design of the air mixing and measuring apparatus due to generous guidelines

Equipment reliability, efficiency, charge migration, and refrigerant charge optimization of refrigeration systems has been widely emphasized as critical development focus. Numerous modeling tools are utilized to predict charge of oil and refrigerant in refrigeration systems during system design. However, there is a lack of experimental validation data to confirm the accuracy of these models. The sampling

In hot arid regions like the UAE, it is of the utmost importance to evaluate and determine the best building orientation. Consequently, the aim of this paper is to investigate thermal performance of building orientations in the UAE. In order to test the thermal performance of building orientations in Sharjah, a real lab-scale house was constructed. It was divided into two zones; one oriented toward

A control-oriented model of an Electrically heated Thermal Energy storage device (ETS) is presented. The ETS consists of bricks heated up to 871 °C with electric coils; heat is discharged with an airflow passing through channels in the bricks. The device stores energy during off-peak periods to meet future on-peak building heating loads. While its rationale is understood, improvement regarding operation

The present study used large eddy simulations (LES) to examine the pedestrian wind velocity distribution for several cases of terraced houses with extensions. Two simulation cases of idealized terraced houses were performed with extension elements in square (E-SQ) and staggered (E-ST) arrangements. These extension elements were treated as secondary roughness. A simulation of the terraced houses without

This paper presents the results of a study investigating the assembly, durability, and leak rate of mechanical joints used in refrigerant and air-conditioning systems. A significant motivating factor of the study is identifying joint types that are suitable for use in systems that employ flammable refrigerants. In the study, three different fitting types were evaluated (press or crimp fittings, compression

Building audits are conducted in many commercial buildings to identify opportunities to reduce energy costs and improve building operation. Because audits require significant effort by building engineers, they are usually only affordable for larger commercial buildings. “No-touch” building audit tools have thus been developed to identify potential savings based on a simplified analysis of building

The main purpose of ventilation system is to meet the requirements of thermal comfort and air quality for the occupants. HVAC designers select air supply devices by using manufacturers’ data, under the assumption that the outflow from the elements is uniform and radially symmetric. Uniformity and symmetry hold only if air velocity vectors have uniform intensities and directions that are perpendicular

With the increased use of flammable refrigerants, there is a need to provide a warning in case of a refrigerant leak that might lead to hazardous conditions. The addition of an odorant has been used for this purpose in other industries and could potentially be used in the HVAC&R industry if suitable odorants could be identified. As an initial step in the evaluation of the use of an odorant, a white