This paper is a keynote address presented at Ventilation, Humidity Control and Energy 24th AIVC Conference.It is a warning for HVAC professionals that are however walking a tightrope. How provide sufficient ventilation for IAQ that yet maintain an appropriate moisture balance without using excessive energy ?Mold is having a severe impact upon us; excessive ventilation and reducing the energy to control the humidity are oftentimes being blamed. Claims have skyrocketed for mold , mildew and humidity-related problems cases.
The goal of this study was the determination of the existing situation in houses with regard to air quality and energy used for ventilation in relation to the health of inhabitants. For the energy policy the Government is considering increased energy requirements for dwellings. They are permanently opposed in doing so by people who are concerned about negative health effect due to increased requirements on for instance air tightness of buildings. To have at least a reference point, they are interested in the existing situation.
Passive cooling strategies require strict adherence to the physical world. Ones imagination creates the flow of ideas that can blossom into a comfortable setting, but the reality of design, construction and cooperation has to be observed and accepted. Physical laws govern as natural processes follow the path of least resistance. In order for us to overcome these laws extra energy is required. That is why passive cooling designers must investigate how to create a comfortable setting by understanding how natural procedures work.
The thermal performance of a monozone building located in Lisbon is studied when night ventilation combined with radiative cooling is used in order to remove the heat from indoors. For simulating the thermal behaviour of the building, a commercial energy building software is used. The potential for radiative cooling in Lisbon, as well as the efficiency of the radiative cooling system were investigated previously. A validated numerical model is used in order to predict the temperature of the air at the outlet of the radiative system.
Cavity wall is often proposed in the building envelope design as a solution for improving the thermal comfort of the inhabitants and reducing the adverse condensation effects on the building fabric. In order to evaluate the thermal effect of ventilated air gaps on building energy demand and comfort, an experimental ventilated cavity wall has been built and tested. The cavity wall separates two ambients at different temperatures that are assumed to be constant over the time required to perform the experimental analysis.
The airflows through a one family prototype building have been simulated. Supply openings in living room and bedrooms have a size of 200 and 400 cm2 respectively. The ventilation system is a passive stack ventilation system, with ventilation chimneys from kitchen, WC and bathroom. The following parameters have been studied: the supply opening areas and heights, the overflow opening areas between bedrooms and hall and between WC/bathroom and hall, the height of the ventilation chimneys and the opening and closing of living room and bedroom doors.
A concept is investigated for the energy efficient control of residential mechanical ventilation in response to outdoor air temperature and the corresponding stack-driven infiltration. The control concept takes advantage of the natural air leakage characteristics of a house and the ability of temperature-driven stack infiltration to provide ventilation air to the house. As the outdoor to indoor temperature difference increases and natural infiltration increases, the fan operation is reduced, thereby minimizing over-ventilation.
Research partners of 10 different countries are developing a computer tool in the framework of IEA ECBCS Annex 36, which helps decision makers to include the most energy-efficient and economic technical retrofit measures into the retrofit of their educational buildings.
The control industry integrates more and more recent innovations, especially on the sector of communication networks (bus), control (fuzzy logic, neural networks...) and informatics (hard-and software) for the development of Building Automation and Control Systems of HVAC plants. These complex control strategies are now being implemented on ventilation systems (hybrid systems, mechanical systems, etc) to satisfy energy and environmental issues.