Min heat questions

[dchomeinspection]

These questions, while energy focused, involve multiple model codes. 68 Degrees is currently listed in IMC and IPMC as min heating requirement for system design. This number appears to be based on some real world public health research.

Here are my questions. Why is appendix D, which is used for determining the system design temps, in the IPC and not the IMC? Does anyone know where the IPMC came up with the room temperature measurement process to determine if a property is meeting the requirement? The commentary provides some guidance, but not the origin of the process or why it's valid. Does anyone know if there are better ways to measure ambient room temp?

 

[Keystone]

The only item I can speak too, the Appendices are not automatically part of the code. The state or local jurisdiction would be required to adopt each appendix.

 

[classicT]

The 68°F heating temperature is also listed in CH. 3 of the IRC; see Section R303.10. As for design criteria for the heating system, see IRC Section R301.2. The AHJ is supposed to complete the subsequent table and list the appropriate Manual J design criteria. Equipment, as per IRC Section M1401.3, must then be designed via ACCA Manual S using the ACCA Manual J design criteria that the AHJ publishes.

R303.10 Required Heating
Where the winter design temperature in Table R301.2(1) is below 60°F (16°C), every dwelling unit shall be provided with heating facilities capable of maintaining a room temperature of not less than 68°F (20°C) at a point 3 feet (914 mm) above the floor and 2 feet (610 mm) from exterior walls in habitable rooms at the design temperature. The installation of one or more portable space heaters shall not be used to achieve compliance with this section.

R301.2 Climatic and Geographic Design Criteria
Buildings shall be constructed in accordance with the provisions of this code as limited by the provisions of this section. Additional criteria shall be established by the local jurisdiction and set forth in Table R301.2(1).

M1401.3 Equipment and Appliance Sizing
Heating and cooling equipment and appliances shall be sized in accordance with ACCA Manual S or other approved sizing methodologies based on building loads calculated in accordance with ACCA Manual J or other approved heating and cooling calculation methodologies.

Exception: Heating and cooling equipment and appliance sizing shall not be limited to the capacities determined in accordance with Manual S where either of the following conditions applies:​

1. The specified equipment or appliance utilizes multistage technology or variable refrigerant flow technology and the loads calculated in accordance with the approved heating and cooling calculation methodology are within the range of the manufacturer's published capacities for that equipment or appliance.
2. The specified equipment or appliance manufacturer's published capacities cannot satisfy both the total and sensible heat gains calculated in accordance with the approved heating and cooling calculation methodology and the next larger standard size unit is specified.

 

[Genduct]

These questions, while energy focused, involve multiple model codes. 68 Degrees is currently listed in IMC and IPMC as min heating requirement for system design. This number appears to be based on some real world public health research.

Here are my questions. Why is appendix D, which is used for determining the system design temps, in the IPC and not the IMC? Does anyone know where the IPMC came up with the room temperature measurement process to determine if a property is meeting the requirement? The commentary provides some guidance, but not the origin of the process or why it's valid. Does anyone know if there are better ways to measure ambient room temp?

The "Mother Ship" for many, if not all things HVAC/ Mechanical is ASHRAE
They provide the Standards for Mechanical Design

They (ASHRAE) have determined that the majority of "Average"people are comfortable at the 68 Deg set point temp under Standard Conditions. There are factors that affect those "Standard " Conditions. For instance, if there is a large amount of glass in the space, the cold surface temp of glass could effect your perception of Comfort.
Ever notice that as you go down the frozen Food Isleat the Supermarket?

That is my understanding as to the source of that "Standard"

 

[Paul Sweet]

If I remember correctly, 70 used to be the usual indoor design temperature for heating. During the 1970s energy crisis the feds tried to limit indoor temperatures to 65 at first, but this got a lot of resistance, so they split the difference and came up with 68.

 

[Genduct]

If I remember correctly, 70 used to be the usual indoor design temperature for heating. During the 1970s energy crisis the feds tried to limit indoor temperatures to 65 at first, but this got a lot of resistance, so they split the difference and came up with 68.

Paul, Are you telling me that a Gov't Agency was capable of COMPROMISE? I am dumbfounded!

 

[dchomeinspection]

The "Mother Ship" for many, if not all things HVAC/ Mechanical is ASHRAE
They provide the Standards for Mechanical Design

They (ASHRAE) have determined that the majority of "Average"people are comfortable at the 68 Deg set point temp under Standard Conditions. There are factors that affect those "Standard " Conditions. For instance, if there is a large amount of glass in the space, the cold surface temp of glass could effect your perception of Comfort.
Ever notice that as you go down the frozen Food Isleat the Supermarket?

That is my understanding as to the source of that "Standard"

Thanks. After additional research I think ASHRAE may be the origin.