Answer :
Final answer:
The effectiveness and economy of general ventilation versus local exhaust systems depend on building specifics, use, and climate. Local exhaust is often more efficient at source contaminant removal, whereas general ventilation affects the entire environment. A tailored combination of both systems may be necessary for optimal air quality and energy efficiency.
Explanation:
When assessing the effectiveness and economy of general ventilation versus local exhaust systems, several factors need to be considered. General ventilation, which includes infiltration, natural ventilation, and mechanical ventilation, affects the entire building's environment by diluting indoor air pollutants with outdoor air. However, its effectiveness can vary based on the building's design, weather conditions, and the behavior of the occupants. On the other hand, local exhaust systems work at the source to remove contaminants and require less air to be moved, making them often more efficient for specific tasks such as removing moisture or smoke from kitchens and bathrooms.
The economic aspect depends on factors such as the amount of thermal power needed to maintain comfort levels, the total thermal energy usage in a year, and the cubic meters of the space being conditioned. In colder climates, homes have been made to maintain warmth through superior insulation and the heat generated by residents, reducing the need for conventional heating systems. Systems like the gravity furnace capitalize on convective loops for efficient heating, which can lead to savings in energy costs.
Ultimately, the choice between general ventilation and local exhaust must be tailored to the specific needs and design of the building, its use, and the local climate. In some cases, a combination of both systems might be necessary to achieve optimal air quality and energy efficiency. The decision should always consider the desired air exchange rate and the levels of indoor pollutants.
