Zones, as discussed here, are defined as areas of the house that are to be independently controlled, typically by their own thermostat. Smaller houses typically only have one zone. If the main criterion for zoning a house is whether it can be served by a single system or not, the designer may want to wait until after doing the load
calculations. The new load calculation software products allow you to easily assign and reassign rooms to different zones and this step can be integrated into the next step of performing the actual room-by-room load calculations. However, evaluating a house for possible zone considerations is still a useful first step.
There are a variety of ways to zone a house and there are several factors to take into account. These include use patterns such as “living” areas and “sleeping” areas.
Thermodynamic zones play an important role as well. These are areas of a house that will behave substantially different because of their relative position or isolation from each other such as upstairs and downstairs, east wing and west wing, etc. Sometimes use patterns and thermodynamic zones do not coincide and you may have to prioritize one over the other. Usually thermodynamic considerations take precedence.
Zoning a house for living/sleeping can generate an energy efficiency. This energy efficiency credit is based on the ability to program the thermostat schedule differently for these two zones thereby saving energy. The real
energy savings of this strategy is highly dependent on the occupant’s proper programming and operation of the thermostats. It can either be accomplished by a single system with zonal control (single system with dual zone components) or by separate systems.
If the dual zone strategy is used, the HVAC design must ensure that it does not have an adverse affect on comfort. If all of the spaces defined as either living areas or sleeping areas are not located in thermodynamically similar zones, special steps may be required to ensure consistent comfort throughout each zone. For example, if a two-story house large enough to require two systems has all of the bedrooms upstairs except the master bedroom, it may be difficult to zone the house for living/sleeping. Because it is a two-story house, it wants to be zoned up/down for thermodynamic reasons. The sleeping zone is split
between two floors and may require further zonal control to achieve satisfactory comfort, resulting in a total of 3 thermostats.
Usually the first question asked from a cost perspective is “Can the entire house be served by a single HVAC system?” In other words, can the total cooling loads, regardless of other considerations, be met by a single 5-ton air conditioner (the largest system typically used in residential construction)? This is not known until the loads are calculated. A preliminary estimate can be made based on square footage and window
area and then later revised if the results of the load calculations change the assumptions.
As homes get more and more efficient, especially in regard to window technologies, larger and larger homes can be served by a single 5-ton system. At some point, other considerations need to be taken into consideration. Things such as adequate airflow (air changes) need to be considered. Does a single 5-ton system at approximately 2000 cfm have enough air moving capability to adequately distribute air throughout a very large house, even if it can meet the steady state cooling load? Also, how susceptible is the house to non-steady state conditions? In other words, what happens if in cooling mode the temperature is inadvertently allowed to substantially exceed the comfort temperature? Will the system be able to catch up in a reasonable amount of time? This can be a critical customer service issue in production homes and is a topic that needs further research.
If the house can be served by a large single system (i.e., 5-tons) but has distinct zones (e.g., upstairs downstairs) it is recommended that those zones be controlled independently (separate thermostats). This can be accomplished by multiple systems or by a single system with zonal controls.
for next step, keep visiting this blog and for new updates subscribe or follow www.mepsite.blogspot.in
calculations. The new load calculation software products allow you to easily assign and reassign rooms to different zones and this step can be integrated into the next step of performing the actual room-by-room load calculations. However, evaluating a house for possible zone considerations is still a useful first step.
There are a variety of ways to zone a house and there are several factors to take into account. These include use patterns such as “living” areas and “sleeping” areas.
Thermodynamic zones play an important role as well. These are areas of a house that will behave substantially different because of their relative position or isolation from each other such as upstairs and downstairs, east wing and west wing, etc. Sometimes use patterns and thermodynamic zones do not coincide and you may have to prioritize one over the other. Usually thermodynamic considerations take precedence.
Zoning a house for living/sleeping can generate an energy efficiency. This energy efficiency credit is based on the ability to program the thermostat schedule differently for these two zones thereby saving energy. The real
energy savings of this strategy is highly dependent on the occupant’s proper programming and operation of the thermostats. It can either be accomplished by a single system with zonal control (single system with dual zone components) or by separate systems.
If the dual zone strategy is used, the HVAC design must ensure that it does not have an adverse affect on comfort. If all of the spaces defined as either living areas or sleeping areas are not located in thermodynamically similar zones, special steps may be required to ensure consistent comfort throughout each zone. For example, if a two-story house large enough to require two systems has all of the bedrooms upstairs except the master bedroom, it may be difficult to zone the house for living/sleeping. Because it is a two-story house, it wants to be zoned up/down for thermodynamic reasons. The sleeping zone is split
between two floors and may require further zonal control to achieve satisfactory comfort, resulting in a total of 3 thermostats.
Usually the first question asked from a cost perspective is “Can the entire house be served by a single HVAC system?” In other words, can the total cooling loads, regardless of other considerations, be met by a single 5-ton air conditioner (the largest system typically used in residential construction)? This is not known until the loads are calculated. A preliminary estimate can be made based on square footage and window
area and then later revised if the results of the load calculations change the assumptions.
As homes get more and more efficient, especially in regard to window technologies, larger and larger homes can be served by a single 5-ton system. At some point, other considerations need to be taken into consideration. Things such as adequate airflow (air changes) need to be considered. Does a single 5-ton system at approximately 2000 cfm have enough air moving capability to adequately distribute air throughout a very large house, even if it can meet the steady state cooling load? Also, how susceptible is the house to non-steady state conditions? In other words, what happens if in cooling mode the temperature is inadvertently allowed to substantially exceed the comfort temperature? Will the system be able to catch up in a reasonable amount of time? This can be a critical customer service issue in production homes and is a topic that needs further research.
If the house can be served by a large single system (i.e., 5-tons) but has distinct zones (e.g., upstairs downstairs) it is recommended that those zones be controlled independently (separate thermostats). This can be accomplished by multiple systems or by a single system with zonal controls.
for next step, keep visiting this blog and for new updates subscribe or follow www.mepsite.blogspot.in
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