Energy Code Changes: What the Design Team Needs to Know -- Session 4 -- Mechanical Systems and the Energy Code
On January 19, Session 4 of the Energy Code Changes series that began earlier this month was held in New York City. This session dealt with Mechanical Systems, which include the Heating, Ventilation, and Air Conditioning systems. The presenter was John Rundell, P. E., LEED AP, Consulting Engineer with Buro Happold.
John, as others mentioned earlier, it is the 2007 NYS Energy Conservation Code (ECCNYS) of 2007 that is the basis for the code that is followed here, and that New York City is making major changes at its local municipal level. He also reviewed the importance of correct and complete submittal documents for each application. (See my earlier blog entries on this)
Of particular importance in the Mechanical Systems area is the P. W. 1 Form, where the energy analysis method is clearly spelled out -- whether it be RES or COM Check, or more detailed energy modeling. It was emphasized here that the supporting documents show the equipment types, efficiency levels, size, as well as duct seal and insulation levels. One of the most common mistakes is for the design team to use and refer to the 2007 ASHRAE 90.1. NYS still uses the 2004 version. Also, teams do not coordinate notes on construction documents with the ECCNYS.
It is important to note that the current version of the ECCNYS resembles the 2003 version of the IECC (International Energy Conservation Code) BUT NYS does NOT actually use this code.
Once again, there are two ways towards compliance: Prescriptive (following certain set levels) or Performance. For each of these, there is the Residential path and the Commercial path. Residential is low-rise. (under four stories) The commercial path is needed for everything else, including higher rise residential.
There are 10 separate chapters, (chapters 5-7 have been abandoned) to this code. The most important chapters are described below:
Ventilation can be either mechanical OR natural, BUT one MUST provide for a means of reducing outside air to the minimum needed for the code (ASHRAE 62.1) Systems larger than 65 MBH MUST have an air-side economizer. Shut-off dampers are needed. Duct sizing is done in regard to the nationally accepted industry standard, SMACC.
Regarding the piping of fluids, controls MUST be used to prevent the re-heating of cooled water, and a three-pipe system is no longer allowed. In systems that provide both heating and cooling, during a change-over between heat or cooling, there must be a 15 degree dead band, and a minimum of four hours must elapse between the change-over. Hydronic heat pumps have a 20 degree dead band (where there is no heating or cooling being done), and must re-use heat from the loop, except in the cases where a system has intelligent controls built in.
Part Load Controls are now needed for systems larger than 300 MBH. A need to allow for a reduction of pump speed by one-third is also needed when a pump is larger than 7.5 H. P.
For Multiple Control Containing Systems, such as Variable Air Volume Systems, design MUST now prevent the unnecessary reheating of air. (Reheating of air is often used and needed in the dehumidification process.) A means to reduce air flow to 30% is needed of systems utilizing re-heating and it must be less than 300 CFM. Exceptions for Variable Air Volume system requirements include areas such as: hospital operating rooms, areas where 75% or more of the air is from solar or Renewable Energy sources, and single duct systems.
All systems must now provide a statement showing that balancing has been competed, an operating manual, HVAC controls manual, and a written narrative.
Heat Recovery for service hot water is now required; thus the need to recover condenser heat. Also, for service hot water, it now required that the first eight feet of pipe be insulated to at least a one-half inch thickness of industry standard pipe insulation.
In summary, a design team MUST refer to the Code often, especially during the early stages of planning and design to make sure that they are able to comply with and accommodate the needed equipment, sizing, controls and insulation levels. In doing so, MUCH time and effort will be saved, and the process will run far smoother to completion. This is where the Integrated Building Design process will serve well.
John, as others mentioned earlier, it is the 2007 NYS Energy Conservation Code (ECCNYS) of 2007 that is the basis for the code that is followed here, and that New York City is making major changes at its local municipal level. He also reviewed the importance of correct and complete submittal documents for each application. (See my earlier blog entries on this)
Of particular importance in the Mechanical Systems area is the P. W. 1 Form, where the energy analysis method is clearly spelled out -- whether it be RES or COM Check, or more detailed energy modeling. It was emphasized here that the supporting documents show the equipment types, efficiency levels, size, as well as duct seal and insulation levels. One of the most common mistakes is for the design team to use and refer to the 2007 ASHRAE 90.1. NYS still uses the 2004 version. Also, teams do not coordinate notes on construction documents with the ECCNYS.
It is important to note that the current version of the ECCNYS resembles the 2003 version of the IECC (International Energy Conservation Code) BUT NYS does NOT actually use this code.
Once again, there are two ways towards compliance: Prescriptive (following certain set levels) or Performance. For each of these, there is the Residential path and the Commercial path. Residential is low-rise. (under four stories) The commercial path is needed for everything else, including higher rise residential.
There are 10 separate chapters, (chapters 5-7 have been abandoned) to this code. The most important chapters are described below:
- Chapter One deals with administrative and enforcement issues. In this area, the 50% exemption rule on alterations (EXCEPT FOR NYC) is found. Specific exemptions -- e.g. historical or low-energy use (less than 3.4 BTU per Square Foot) buildings are also covered.
- Chapter 2 gives the definitions BUT NOT TECHNICAL terms.
- Chapter 3 defines the Climate Zones, which are VERY critical in the design and application process. Many mistakes are made here!!! For NYC, the Climate Zone specifies that the following Design Temperature Conditions be used: 89 / 73 degrees F. for cooling and 13 degrees for heating -- NO Exceptions here; one CANNOT design a building to handle more than these parameters.
- Chapter 4 covers the Mechanical Requirements, Performance, R-Values of duct insulation, duct leakage allowances, HVAC types. Chapter 4 also specifies that sticker MUST be place in or on the building that gives this information in an prominent location. Electric Resistive Heat Sources have much more stringent requirements. It is also now a requirement that each system have its own control, and more specifically, each residential dwelling MUST have a programmable thermostat. For ducts that run OUTSIDE of the envelope, the R-Value for insulation is now 8, and building cavities can no longer be used as a duct system. Piping must have an R-2 value at a minimum if the carrying fluid is lower than 55 degrees F., or greater than 105 degrees F. Piping insulation is now required on all hot water re-circulation systems, such as those found in hotels. Equipment sizing is done either by Manual J (for simpler projects) or ASHRAE. One MUST select equipment to meet minimum Annual Fuel Utilization Efficiency (AFUE) These are: 90% for gas furnaces, Oil is 82%, while gas boilers are still 82% Heat Pumps cannot fall below 8.2 EER.
- Chapter 8 spells out the commercial code in more detail. Here, we see the option of using ASHRAE 90.1 or the prescriptive method, or we can use a more involved energy modeling method to prove compliance. We will note the presence of Mandatory Provisions that MST be met, such as Heating and cooling equipment controls, HVAC equipment minimum efficiency levels, envelope dampers must NOT leak more than 3 Cubic Feet Per Minute, the use of gravity dampers is limited to buildings of less than three stories, and EACH system MUST have a separate control. We also see the need for air economizers on recovery systems, and the system of greatest load MUST be the basis for the load calculation. Sequenced controls are required for complex systems, and once again there is NO ALLOWANCE for over sizing of equipment; this means that a client cannot install additional equipment to facilitate a faster morning recovery of heat or cooling. HVAC Performance Requirements MUST be met, and federal codes supersede the state or local codes here. For many mechanical systems, the Coefficient of Performance (COP) is now greater than six; hence the new code has taken this into account, and one MUST refer to Chapter 8 for the specific levels needed here.
Ventilation can be either mechanical OR natural, BUT one MUST provide for a means of reducing outside air to the minimum needed for the code (ASHRAE 62.1) Systems larger than 65 MBH MUST have an air-side economizer. Shut-off dampers are needed. Duct sizing is done in regard to the nationally accepted industry standard, SMACC.
Regarding the piping of fluids, controls MUST be used to prevent the re-heating of cooled water, and a three-pipe system is no longer allowed. In systems that provide both heating and cooling, during a change-over between heat or cooling, there must be a 15 degree dead band, and a minimum of four hours must elapse between the change-over. Hydronic heat pumps have a 20 degree dead band (where there is no heating or cooling being done), and must re-use heat from the loop, except in the cases where a system has intelligent controls built in.
Part Load Controls are now needed for systems larger than 300 MBH. A need to allow for a reduction of pump speed by one-third is also needed when a pump is larger than 7.5 H. P.
For Multiple Control Containing Systems, such as Variable Air Volume Systems, design MUST now prevent the unnecessary reheating of air. (Reheating of air is often used and needed in the dehumidification process.) A means to reduce air flow to 30% is needed of systems utilizing re-heating and it must be less than 300 CFM. Exceptions for Variable Air Volume system requirements include areas such as: hospital operating rooms, areas where 75% or more of the air is from solar or Renewable Energy sources, and single duct systems.
All systems must now provide a statement showing that balancing has been competed, an operating manual, HVAC controls manual, and a written narrative.
Heat Recovery for service hot water is now required; thus the need to recover condenser heat. Also, for service hot water, it now required that the first eight feet of pipe be insulated to at least a one-half inch thickness of industry standard pipe insulation.
In summary, a design team MUST refer to the Code often, especially during the early stages of planning and design to make sure that they are able to comply with and accommodate the needed equipment, sizing, controls and insulation levels. In doing so, MUCH time and effort will be saved, and the process will run far smoother to completion. This is where the Integrated Building Design process will serve well.
Posted by Alan L. Englander at 1/24/2010 4:58 PM 
Categories: Ventilation, Options and Challenges for Compliance, NYS Energy Conservation Code, Integrated Building Design, Renewable Energy Sources, System Types, International Energy Conservation Code, Service Hot Water, HVAC, Air Infiltration, Energy Conservation, Building Insulation, ASHRAE 90.1
Categories: Ventilation, Options and Challenges for Compliance, NYS Energy Conservation Code, Integrated Building Design, Renewable Energy Sources, System Types, International Energy Conservation Code, Service Hot Water, HVAC, Air Infiltration, Energy Conservation, Building Insulation, ASHRAE 90.1
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