ventilation

In moderate climates, adventitious ventilation helps in keeping the water vapor balance in a building under control. This does not hold in hot and humid climates, where the outside air is a moisture source. Adventitious ventilation should be avoided in such climates and intended ventilation flows must be dried before entering the space. Anyhow, could adventitious ventilation also generate moisture problems in moderate climates? To get an answer, a reference case was analyzed with the air leakage distributed over facades and roof.

In order to facilitate nationwide analysis of ventilation and indoor air quality issues in residential buildings, a set of homes has been defined to represent the housing stock of the United States. This so-called 'suite of homes' is based on two residential housing surveys, the U.S. Department of Energy Residential Energy Consumptions Survey (RECS) and the U.S. Census Bureau American Housing Survey (AHS). The RECS dataset includes about 6000 U.S. residences and the AHS covers about 60000, and are both intended to periodically characterize the U.S. housing stock.

With the application of part L2 of the Building Regulations in the UK, new buildings with excessive air leakage have no longer been acceptable. All new commercial and public building over 1000 m2 must be tested for airtightness. An air permeability formula measures the envelope of walls, roof and ground floor area. This paper explains why bother about air leakage, and what desginers and constructors must do, and how the testing for airtightness should be carried out. The essential message is : build tight - ventilate right.

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 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.

For the multi-room ventilation calculations, bi-directional flows or counter flows in openings have been rarely taken into consideration and only uni-directional flows have been allowed for the calculation. It stands to reason that the calculation requires quite sophisticated scheme and the appearance of the bi-directional flows are restricted only to a limited number of openings neighboring the neutral plane of the building and also the flow rates may be too little to affect the total building

At the new institute building of Fraunhofer ISE, both mechanical and free night ventilation is used for passive cooling of the offices. The results from a monitoring of room temperatures in 21 office rooms during summer 2002 show that room temperatures exceeds 25 C in less than 8 % of the working hours, even at high ambient air temperatures. In two offices, experiments were carried out in order to determine the efficiency of night ventilation dependent on air change rate, solar and internal heat gains. During the experiments, meteorological data, air change rates, air temperatures (incl.

This paper presents the development of a simulation tool based on the Matlab computational environment for building temperature performance analysis with automatic control. The simulation tool contains mathematical models for buildings, HVAC (Heating, Ventilation and Air Conditioning) systems, sensors, weather data and control algorithms. The building mathematical model is described in terms of statespace variables, with a lumped approach for the room air governing equations energy and mass balances. In this context, the simulation tool structure and components are explained.

This paper describes a performance-based evolution model using Genetic Algorith as the evolution algorithm and CFD as the evaluation mechanism. The advantages of such an evolutionary performance-based design approach is that diverse instances of the state space can be investigated in relation to specific goal requirements that will enhance the possibility of discovering a variety of potential solutions. The model allows the user to explore and visualize the design evolution and its form generation in an attempt to stimulate the designer creativity that might contribute to their output.

A comfortable indoor climate environment is necessary for modern buildings and therefore the Heating, Ventilation and Air-Conditioning (HVAC) systems are widely used. Faults or disturbances are normally unavoidable in the systems and they will lead to more energy consumption or degradation of comfort level of indoor climate. Energy consumption is useful to detect the