ventilation

Natural ventilation is generally accepted as the preferred ventilation option as it is a healthy and energy-efficient means of supplying fresh air to a building. In the USA it is seldom being applied as most climate zones are considered unsuited to apply natural ventilation, mostly due to perceived uncontrollability and very humid and hot or very cold seasons. For mid and high rise apartment buildings the option of natural ventilation is virtually disregarded because the tradition of full air conditioning is so well established.

The indoor climate system, which serves a building with a proper indoor air quality and thermal comfort, has been predominantly designed based on the initial cost. A life cycle approach could improve both the economic and environmental performance. For example, the energy use could decrease. There has been a lack of knowledge, models and simulation tools for determining the life cycle cost (LCC) for an indoor climate system. The objective of this paper is to present a model for calculating the LCC for indoor climate systems. Focus is on indoor climate systems for premises and dwellings.

It is well known that humidity influences cooling load, thermal comfort and durability of buildings and various items in them. Many works on prediction of humidity variation in a room have regarded the humidity as unique in a space. However, it does depend on air movement. This paper describes calculations of minute moisture distributions in a room affected by moisture buffering of porous walls. The air velocity distribution is calculated by CFD using two different turbulence models. Then the heat and vapor transient transport in walls and space is calculated.

A universal lumped model is developed with the aim to predict the thermal performance of Double Skin facade. Three modules – ventilation, heat transfer and penetration - are coupled to comprehensively describe the energy and mass transfer processes. The unknown parameters, resistance coefficient and heat convection coefficient, are discussed and estimated. The influences of cavity shading position, cavity depth and ventilation height on energy performances are analyzed at the end of the paper based on the simulation results.

The deep hot hyperarid valley between Israel and Jordan presents unique design and construction challenges in terms of energy conservation and thermal comfort. Winters are relatively mild, summers are extremely hot during the day and at night the air temperature remains above 25°C.  Such conditions present real challenges in this sparsely populated yet rapidly developing region. Such development depends on the ability to provide acceptable indoor environments at a low energy investment.

Nowadays, important efforts are made to reduce the residential building energy consumption. In this context, a growing interest for heat recovery ventilation has been observed during the last decades. The present paper focuses on a new single room ventilation with heat recovery. Double flow ventilation is achieved through the integration of the unit into windows ledges. The developed device is particularly suitable compared to traditional centralized heat recovery ventilation units for retrofitted houses due to the absence of air extracting and air pulsing ducts through the house. 

Heat recovery ventilation became an unavoidable element of a passive or nearly zero energy building in Northern and Central Europe countries. Airtightness standards became very tight so that the building is compatible with this ventilation system. As frosting of heat recovery unit consumes a lot of electrical energy, a buried pipe system to smooth air temperature variations became also a necessary system in order to avoid defrosting.

As a consequence of the energy and environmental issues, it is necessary to reduce the energy consumption of buildings. So, the air tightness of building envelopes is being improved and the air change rate due to infiltration is decreasing. It is then even more important than in the past that the buildings are equipped with well designed and working ventilation systems in order that the air renewal within buildings is ensured. In this context, the market of balanced ventilation systems with heat recovery for dwellings is growing. 

In order to improve the quality of ventilation systems, assessments are widely used. In this paper, 3 main assessment levels are distinguished based on the number of ventilation systems to be assessed and the assessment objective.

Few studies focus on commercial low-rise buildings which are often characterized by low-cost constructions materials and weak energy performances. For these large volumes, the heat transfers with the roof and the ground are prevalent. In this article, we show how the analysis of heat transfers through both the roof and the ground can achieve their thermal performance. The roof design and its opening systems is a key factor of the thermal and lighting performance.