How to Read Manual J Reports

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prime

Subtitle: 
If you know what to look for, it’s easy to check for accuracy

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When you enter the world of building science — whether through building a house, becoming a home energy rater/building analyst, or just hanging out in cyberplaces like this — everyone talks about the importance of getting actual heating and cooling load calculations based on ACCA Manual J. A great number of HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractors sell and install oversized equipment with air distribution systems that don’t work because these contractors base their choices on rules of thumb.

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How to Read Manual J Reports

Prime: 
prime

Subtitle: 
If you know what to look for, it’s easy to check for accuracy

Images: 

When you enter the world of building science — whether through building a house, becoming a home energy rater/building analyst, or just hanging out in cyberplaces like this — everyone talks about the importance of getting actual heating and cooling load calculations based on ACCA Manual J. A great number of HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. contractors sell and install oversized equipment with air distribution systems that don’t work because these contractors base their choices on rules of thumb.

read more

Proper Sizing Isn’t the Real Reason for HVAC Design

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Subtitle: 
Yes, size matters, but another factor matters more

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Many people seem to think HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. design means you get a load calculation (Manual J in the ACCA protocols) so you know what size system to put in. Hey, that’s a great start. It’s way better than just using a rule of thumb or Manual E (for eyeball).

But there’s so much more to real HVAC design than simply finding out how much heating and cooling a building needs when it’s at design conditions. And we might as well start with the fact that my first statement is incorrect: The load calculation does not tell you what size system you need.

read more

Proper Sizing Isn’t the Real Reason for HVAC Design

Prime: 
prime

Subtitle: 
Yes, size matters, but another factor matters more

Images: 

Many people seem to think HVAC(Heating, ventilation, and air conditioning). Collectively, the mechanical systems that heat, ventilate, and cool a building. design means you get a load calculation (Manual J in the ACCA protocols) so you know what size system to put in. Hey, that’s a great start. It’s way better than just using a rule of thumb or Manual E (for eyeball).

But there’s so much more to real HVAC design than simply finding out how much heating and cooling a building needs when it’s at design conditions. And we might as well start with the fact that my first statement is incorrect: The load calculation does not tell you what size system you need.

read more

Converting Heating and Cooling Loads to Air Flow Needs

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Subtitle: 
Here’s how Manual J software takes your inputs and gives you both the BTU/hour and cfm needed for each room

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When you embark on the project of educating yourself about building science, one of the first things you encounter is the concept of heating and cooling loads. Every building has them. (Yes, even Passive House projects.) That’s why we do heating and cooling load calculations. We enter all the details of the building, set the design conditions, and get the heating and cooling loads for each room in the building.

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