Passive Building Cooling and Heating
Before the introduction of electricity and air-conditioning in buildings in the early 1900s, building designs relied primarily on natural ventilation to ensure adequate fresh air and acceptable thermal comfort. Because of the benefits associated with natural ventilation - reduced capital costs, maintenance, and energy usage – there is a growing interest in re-introducing passive design principles into modern buildings.
Services Offered
Let us guide you in using the forces of nature to help temper your indoor environment. We offer the following services: * Thermal loads calculation * Natural ventilation predictions * Thermal comfort predictions For more information, please continue reading.
Thermal Loads Reduction
Since natural ventilation can only achieve limited cooling, a key design challenge is to reduce the heat gains in spaces inside a building. Greenplan can assist you to introduce basic passive design features into your concept design that will result in reduced heat loads throughout your building. We analyse factors such as building orientation, size of windows, external shading devices, glazing types, and internal heat loads from lights, in order to make passive cooling more effective. Alternatively, where cold buildings are a concern, we can see how the building design can be improved to gather more solar energy during the day. Rock stores and Trombe walls are some of the features that can be used to improve the thermal conditions.
Natural Ventilation Predictions (non-CFD method)
We can give rough predictions of the rate at which air will be exchanged in a building, and advise on the required size and position of air inlet and outlet openings to achieve given flow rates of fresh air, based on local weather data. The use of CFD (link) can provide much more detailed predictions.
Thermal Comfort
ASHRAE Standard 55 defines thermal comfort as that condition of mind that expresses satisfaction of humans with their thermal environment, or in simple terms, whether they feel too hot or too cold. As one can imagine, thermal comfort is a very important issue for occupants of buildings. Because thermal comfort is a subjective experience, it is very difficult to define. One needs to take into account a range of environmental, activity-related and personal factors when deciding what makes a comfortable indoor environment. The best that you can realistically hope to achieve is a thermal environment that satisfies the majority of people in a particular indoor space. There is a common misconception that room temperature alone is the only measure of thermal comfort. In reality, there are six primary factors that play a role in determining thermal comfort. These can be divided into environmental and personal factors. Environmental factors include: * air temperature * temperature of walls, floors, ceilings, and other surfaces surrounding you * humidity and * velocity of airflow across your skin Personal factors include: * how well your body is being insulated by the clothing you wear and * how physically demanding your activities are. Greenplan uses sophisticated modelling software to determine thermal comfort levels in both naturally and mechanically conditioned building spaces. These simulations take into account all the above parameters that influence our perception of thermal comfort. We can generate data on expected subjective thermal comfort levels in a building, clearly showing when a passive system will be adequate and when additional mechanical conditioning might be required.