English

Several configurations of air to air ERHXs exist, they include heat recovery ventilators and energy recovery ventilators. They are placed in ventilation units, unitary air conditioners, and air-handling units that take in outdoor air while venting indoor air.
Those air to air energy recovery heat exchangers reduce HVAC energy consumption and reduce the required air-conditioning capacity of the building too.
But a periodic cleaning to maintain effectiveness is necessary. During the heating season in cold climates, a frosting protection may be necessary.

The use of humidistats to control air conditioners may create mold problems mainly in houses unoccupied for an extended period. This article looks for the best approach to control humidity in empty homes during hot and humid summers. Several solutions are proposed.

This paper deals with the comparison of two kind of methods for cleaning of air ducts. One is mechanical brushing with different brushes and the second one with compressed air cleaning. In the laboratory and field tests it appeared that the brushing methods were more efficient in metal ducts, whereas the compressed air cleaning was more efficient in plastic ducts. Concerning the oils residues stuck with dust, they were difficult to remove with both the cleaning methods.

The question is if the dedicated outdoor air systems can meet ASHRAE's air change design criteria. The standard 62 air change per hour design criteria does not inhibit the use of a separate constant volume ventilation air system (DOAS). This article shows the strong benefits of DOAS : this system with high induction diffuserscan exceed the performance of a conventional all-air VAV system under design conditions from a diffuser performance, space air mixing, and ADPI perspective.

In this study, the air flow in a small scale industrial hall is simulated numerically using two different computing codes, the commercial flow solver with a high-Reyholds number turbulence model and a university code with a low-Reynolds number turbulence model. The results are compared with measurements. Two different air supply arrangements with grille or nozzle types of air terminal devices are studied, both with isothermal and non-isothermal boundary conditions.

The efficiency of an air diffusion system consists of two factors. The first is the ability of the system to remove heat and contaminants out of the ventilated room. This is most often characterized using temperature removal and contaminant removal efficiency. The second, seldom considered, factor is the uniformity of the temperature and contaminant distribution within the ventilated space. This factor describes how much the maximum contaminant concentration or minimum temperature differs from the average value.

The contaminant removal efficiency and the uniformity of contaminant concentration in the occupied zone of a room were studied in scale model with the following varying parameters : occupied zone obstruction level, air distribution system, air change rate, cooling load, contaminant sources distribution.
Results show that obstruction level, air distribution system, air change rate and cooling load have a small influence on contaminant removal efficiency and uniformity of contaminant concentration.

There is a variety of different methods consulting engineers use to design room system, room air diffusion, such as assumption of perfect mixing, design methods employing the empirical relations determined through research, air jet theory and computational fluid dynamics (CFD) codes. The most common design methods based on air jet theory allows only for the prediction of extreme values of air velocities and air temperatures in the occupied zone.

Dryness is still one of the major complaints concerning indoor air quality in office buildings and respective nonindustrial environments. Dampness in buildings in terms of excess amounts of water in the solid parts, and the harmful consequences have been discussed vigorously in recent years. Indoor air humidity, which means water vapour in the indoor air, has been given less attention.

Temperatures in buildings with low and high thermal mass levels have been monitored during the warm period in Kenya. The effect of thermal mass in lowering the maximum indoor daytime temperatures has been evaluated as very effective.