Economically optimal dimensioning of a counterflow and crossflow heat exchanger for free cooling

During the cold seasons, it is possible to use ambient air to cool down the coolants in air-conditioning or other refrigeration applications. Applying this free cooling reduces the energy costs of a refrigeration machine. This paper presents a general method for the economically optimal dimensioning of a free cooling system in which a heat exchanger of the counterflow or crossflow type is applied to the heat transfer between the ambient air and the coolant.

An evaluation of natural ventilation and comfort of a multi-storey university office building

Ventilation and comfort assessment of buildings is not a new practice in post occupancy evaluation (POE) of buildings. Most evaluations have been based on perceived assessments by the occupants collated through questionnaires asking for a Yes/No response or qualitative scale rating. While this study does not deal with a POE survey, it was initiated by the lack of comfort and overheating complaints of the occupants of the subject university building.

Aspects of air and heat distribution in low energy residential buildings

In highly insulated residential buildings, complying with the Passive House Standard, the space heat demand can be covered by air heating at air flow rates given by air quality requirements, without the need for additional air re-circulation or for a water heating system. The air distribution system is kept compact. In a common concept the supply air terminal is located above the door to the corridor. Such configurations were evaluated for typical air transfer devices and extreme supply temperatures.

Heat recovery in building envelopes

Infiltration has traditionally been assumed to contribute to the energy load of a building by an amount equal to the product of the infiltration flow rate and the enthalpy difference between inside and outside. Some studies have indicated that application of such a simple formula may produce an unreasonably high contribution because of heat recovery within the building envelope. The major objective of this study was to provide an improved prediction of the energy load due to infiltration by introducing a correction factor that multiplies the expression for the conventional load.

Using forced ventilation to mitigate mold growth in existing multi-family housing

Increasing emphasis on energy-efficiency has many jurisdictions enacting stricter energy codes. Yet, these same green building codes typically do not adequately address ventilation when a building envelope is designed to both minimize infiltration/exfiltration and maximize thermal efficiency. Our company investigated an apartment complex in Southern California, U.S.A. that was designed 25% more thermally efficient than required by State Code. Within months of occupancy, the first complaints of biological growth at windows and closets occurred.

Mold in dwellings : field studies in a moderate climate

Mold in dwellings is a persisting complaint in moderate climates. Nine parameters intervene in it: (1) climate, (2) inside temperature, (3) vapor release, (4) ventilation, (5) lay out, (6) envelope thermal performance, (7) sorption inside, (8) presence of preferential condensation surfaces and (9) type of finish. Exterior climate acts as boundary condition while inside temperature, vapor release and ventilation belong to the living habits. The five others are design and construction related.

Energy saving through the use of a supply air window

In Arctic and sub-Arctic climates, such as those in Scandinavia, multiple-glazing windows that consist of at least three panes are widely used. Typically, the replacement air for the extracted air, especially in low-cost accommodation with forced extraction, enters the interior space in the form of leakage flow through the window jambs and the walls or through the supply air vents. The temperature for the air entering the room is close to that of the outdoor air, which may cause a sensation of draft.

Humidity sensitive systems is 20 years old

During the last 20 years, the humidity sensitive ventilation system evolved to products increasingly simplified thus standardised. At Aereco, there were 5 generations of extract units, each modification of product was due to a change in the acceptation criteria. In many countries, systems with variable airflows are accepted and recognised ; regulations moved. In other countries, the orthodoxy of the constant airflow of an air change per hour remains in force for simplifying reasons or by ignorance of the real interest.

Weather resistive barriers : new methodology for their evaluation

Effective weather resistive barriers (WRB) perform important functions in retarding waterentry into walls and in controlling water vapor movement as well as the amount of energyattributed to air leakage (Burnett, 2000; Weston et al 2001). Recognizing this, a public andprivate sector research consortium was established to develop reliable and precise methodsfor evaluating their performance.This paper, third in a series, provides an overview of the most significant results obtainedduring the consortium work.

Sick building syndrome : indoor quality and performance implications

Findings about sick building syndrome in Sydney’s offices are presented. The aim is to ascertain whether perceptions of sick building syndrome in offices impact on discrete aspects of workplace performance and management. One hundred offices in the Sydney