Significant changes to the commercial provisions in 2012 IECC
Significant changes to the 2012 International Energy Conservation Code (IECC) impact architects, engineers, code officials, and other building design professionals.
- Understand the significant changes in the commercial provisions in 2012 IECC.
- Learn about the newly added sections to the code.
The 2012 edition of the International Energy Conservation Code (IECC) expanded the code requirements for building systems and equipment over those of the 2009 edition to focus on conservation over the life of the building. A major formatting change was also made in that the residential and commercial provisions were split up to provide the commercial provisions in the front with a “C” preceding each section and the residential provisions in the back with a preceding “R.”
The code sections noted in this article are merely to facilitate discussion of the potential requirements that may be applicable in the 2012 IECC. This article is not intended to be a replacement for any of the referenced code/standard documents.
Section C401, Scope & Application of Commercial Energy Efficiency, has been modified to require new buildings designed using the prescriptive approach to comply with an additional efficiency package option in Section C406 and buildings designed using the performance-based approach to have energy costs ≤ 85% of the standard reference design building. Compliance with ASHRAE Standard 90.1 is still available as an option. The new section, Additional Efficiency Package Options (C406), requires new buildings to comply with at least one of three subsections: efficient HVAC performance, efficient lighting, or on-site supply of renewable energy (see Figure 1). Individual tenant spaces must comply with one of the first two unless the entire building complies with the on-site supply of renewable energy specifications or the tenant scope falls within the limitations of an alteration as noted in C101.4.3.
Lighting and efficiency
There were several changes regarding lighting, some of which increase the number of options available to designers and others that are more restrictive with the intent of increasing overall efficiency. The exception to complying with the Electrical Power and Lighting Systems (C405.1) for dwelling units within commercial buildings was made more stringent by increasing the required number of permanently installed high-efficiency lighting fixtures from 50% to 75%. Luminaries of rated power less than 100 W, equipment rooms and electrical/mechanical rooms, and daylight spaces complying with Section C405.2.2.3.2 are excluded from the Light Reduction Controls Section (C405.2.1.2) requirements.
The 5,000-sq-ft threshold on automatic time switch control devices (C405.2.2.1) was removed, and all buildings are now subject to the requirement. Occupancy sensors are now required in all meeting rooms, storage closets, and other spaces 300 sq ft or less (C405.2.2.2) and must be either manual on or controlled to automatically turn on the lighting to not more than 50% power. Additionally, daylight zone controls can no longer exceed 2,500 sq ft (C405.2.2.3), and the prescriptive approach requires compliance with new Section C405.2.2.3.2, Automatic Daylighting Controls, which requires the capability to automatically reduce lighting power in response to available daylight. Dedicated controls are now required per a new section (C405.2.3) for display and accent lighting, supplemental task lighting, and other similar specific applications.
The interior lighting power allowances in Table C405.5.2(1) have decreased for fire stations, offices, retail, and warehouses. The total interior lighting power allowance (C405.5.2) can now be determined using the building area method as well as the returned space-by-space method using newly added Table C405.5.2(2). The space-by-space method was previously known as the “tenant area or portion of building method” in the 2003 IECC before being removed in the 2006 revision.
Several updates regarding fenestration were made that could potentially increase construction costs. The rating of visible transmittance (VT) was added to the Fenestration Product Rating section (C303.1.3) and its corresponding Table C303.1.3(3). The maximum allowable fenestration area as a percent of wall area was reduced from 40% to 30% (C402.3.1). Increased fenestration is permitted, however, with daylighting controls provided that at least 50% of the conditioned floor area is within a daylight zone and the VT is greater than or equal to 110% of the solar heat gain coefficient (SHGC). Automatic daylighting controls specified in Section C402.3 must comply with the dimming requirements in section C405.2.2.3.2.
Values were modified in Table C402.3, Building Envelope Requirements: Fenestration, and the maximum SHGC for projection factor (PF) values more than 0.2 are calculated with the newly added complementary Table C402.3.3.1, SHGC Adjustment Multipliers. Area-weighted PF values are no longer permitted to be calculated and used (C402.3.3). See Figure 2 for a description of glazing properties.
A new section was added (C402.3.2) that requires building areas of certain occupancies greater than 10,000 sq ft with ceilings greater than 15 ft to have at least 50% of the floor area as a daylight zone under skylights. Furthermore, the skylight area to daylight zone must be at least 3% with a VT of 0.40 or the skylight effective aperture must be at least 1% as determined by newly added Equation 4-1, Skylight Effective Aperture. Four exceptions were added, excluding the following:
- Climate zones 6 through 8
- Designed lighting power densities <0.5 W/sq ft
- Areas where existing objects block sunlight for more than 1,500 daylight hours per year from 8 a.m. to 4 p.m.
- Spaces where daylight zones under rooftop monitors are greater than 50% of the enclosed floor space.
Within the affected occupancies, all lighting in daylight zones is required to be controlled by multilevel lighting controls (C402.3.2.1), and skylights in most of those areas must have a measured haze factor >90%, with the exception of skylights designed to exclude direct sunlight from entering occupied spaces (C402.3.2.2).
A maximum SHGC of 0.40 in climate zones 1 to 3 for vertical fenestration ≥ 6 ft above the finished floor (C402.3.3.2) and a maximum SHGC of 0.60 in climate zones 1 to 6 for skylights above daylight zones provided with automatic daylighting controls (C402.3.3.3) are now permitted. A maximum U-factor of 0.9 in climate zones 1 to 3 and 0.75 in climate zones 4 through 8 for skylights above daylight zones provided with automatic daylighting controls is also permitted (C402.3.3.4).
Requirements and limitations on how the SHGC and VT for dynamic glazing is to be calculated and used are now specified (C402.3.3.5). Area-weighted averages are permitted to satisfy U-factor requirements within and only within each fenestration category listed in Table C402.3 (C402.3.4), potentially lowering the cost of construction.
Except for climate zones 1 through 3, a continuous air barrier is required around the thermal building envelope (C402.4). Subsection C402.4.1.1 details the construction requirements of the air barrier and subsection C402.4.1.2 lists three compliance options, one of which is required to be met: materials, assemblies, or full building testing (see Figure 3). A table of maximum fenestration assembly leakage rates is provided in Section C402.4.3.
Unless required to comply with IBC Section 715 or 715.4 or UL 1784, doors and access openings from conditioned spaces into shafts, chutes, stairways, and elevator lobbies shall meet the fenestration requirements or be sealed per a newly added section (C402.4.4). Stairway, shaft, and outdoor air intakes and exhausts shall be provided with motorized dampers limited to a leakage rate of 4 cfm/sq ft. Gravity dampers meeting a 20 cfm/sq ft leakage rate are permitted as an exception for outdoor intakes and exhausts in climate zones 1 to 3, buildings less than 3 stories, as exhaust and relief dampers, and where the design outdoor air intake or exhaust capacity is ≤ 300 cfm. Dampers smaller than 2 ft in either dimension are permitted a leakage rate of 40 cfm/sq ft (C402.4.5).
Exposed outdoor piping insulation must now be protected from degradation, and use of adhesive tapes is not permitted (C403.2.8.1). Some exceptions to piping insulation requirements (C403.2.8) were also modified. The temperature range in exception 3 was decreased from 55 to 105 F to 60 to 105 F. Exception 5 no longer applies to piping 4 ft or less in length but instead to strainers, control valves, and balancing valves on piping with a diameter of 1 in. or less. Exception 6 was added that applies to buried piping conveying fluids ≤ 60 F.
Table C403.2.8, Minimum Pipe Insulation Thickness, was expanded, and the insulation thicknesses for very hot fluids and steam were increased tremendously; however, a footnote was added allowing a thickness reduction for direct-buried heating and hot water system piping. An exception was added to Section C404.5, Pipe Insulation, for heat-traced piping systems, specifying that they must meet the insulation thickness requirements per the manufacturer’s installation instructions.
A minimum insulation of R-3.5 is now required for radiant panels, associated U-bends and headers, and the bottom surfaces of structures incorporating radiant heating (C402.2.8).
Several changes were made to mechanical system requirements in the update from the 2009 to 2012 IECC. More equipment was added to Tables C403.2.3(1) through (8) and values were modified—mostly to be more restrictive, which could increase the costs of construction. Table C403.2.3(5) was modified to decrease minimum gas and oil-fired boiler efficiencies, however. Liquid-to-liquid heat exchangers must now meet the test procedure AHRI 400 (Table C403.2.3(9)).
Section C403.2.3.1, Water-Cooled Centrifugal Chilling Packages, an exception to Section 503.2.2 in the 2009 IECC, is now its own subsection. The Adjusted Maximum Full Load kW/ton was replaced with the Adjusted Minimum Full-Load coefficient of performance (COP). The equations defining terms have changed to be functions of Celsius instead of Fahrenheit and refer the user to Table 6.8.1C of AHRI Standard 550/590 instead of Table 503.2.3(7). The range of fluid temperature leaving the evaporator and condenser was increased from 38 to 102 F to 36 to 115 F, and a lift between 20 to 80 F is now required for this section to be applicable.
Automatic start controls capable of automatically adjusting the daily start time of the HVAC system are required for each HVAC system (C403.2.4.3.3). The occupant load requirement for demand control ventilation (C403.2.5.1) was lowered from 40 people to 25 people per 1000 sq ft, however an additional exception was added excluding the demand-controlled ventilation provided for process loads only.
Fans and air movement
The scope of the prescriptive HVAC systems and equipment requirements (C403.3) expanded due to the removal of the second paragraph exempting certain fan systems. Variable air volume (VAV) fan control (C403.4.2) expanded the applicability of the section from VAV fans with motors ≥10 hp to motors ≥7.5 hp; however, an additional exception was added excluding vane-axial fans with variable-pitch blades. Static pressure sensors used to control VAV fans shall be positioned such that the controller setpoint is ≤1/3 the total design fan static pressure with the exception of systems with zone reset controls (C403.4.2.1). Sensors located past duct splits need a sensor in each major branch.
Some exceptions to energy recovery ventilation system requirements were modified (C403.2.6). Exception 3 was modified to also require that the exempt space not be cooled, and exceptions 5 and 6 now refer to climate zones instead of specific climate qualities. Furthermore, exception 8 was added which excludes systems where the largest source of air exhausted at a single location at the building exterior is <75% of the design outdoor airflow rate, and exception 9 was added that excludes systems expected to operate <20 hours/week at the outdoor air percentage covered by Table C403.2.6. Single-zone VAV systems must now comply with the constant volume fan power limitation (C403.2.10.1) with the newly added exception of vivariums. Exception 3 excluding fans exhausting air from fume hoods in the 2009 edition was deleted, and additional devices were added to Table C403.2.10.1(2), Fan Power Limitation Pressure Drop Adjustment.
The entire Economizer Requirements section (C403.3) and all of its subsections were modified extensively in the 2012 update. Exceptions to the requirements were added including systems expected to operate <20 hours/week, systems that serve residential spaces where system capacity is less than five times the requirement listed in Table C403.3.1(1), and others. Climate zones 2A, 7, and 8 now require economizers (Table C403.3.1(1)), and the economizer requirement was also made more stringent by decreasing the cooling system requirement from 54,000 Btu/h to 33,000 Btu/h.
Compliance with Sections C403.3.1.1.1 through 4 is mandatory, and Section C403.3.1.1.2 requires that economizer damper sequencing with mechanical cooling equipment cannot be controlled by only mixed air temperature except for systems controlled from space temperature, such as single-zone systems. Section C403.3.1.1.3, High-Limit Shutoff, now refers users to newly added tables C403.3.1.1.3(1) and (2), and section C403.3.1.1.4 requires excess air relief to avoid over pressurization. Economizer Design (C403.4.1) limits the maximum water-side pressure drop to 15 ft of water, and economizer systems are required to be integrated with mechanical cooling systems. Economizers also cannot increase building heating energy use.
Pools and spas
The section and subsections regarding pools (C404.7) were expanded to include in-ground spas. Heaters are required to have an on/off switch mounted outside the heater. Section C404.7.2 was modified for clarity to include built-in timers. Pools heated >90 F are no longer required to have a cover with a minimum insulation value of R‑12, and the exception for vapor retardant covers was made more stringent by increasing the site-recovered energy used for heating from 60% to 70%.
Mechanical Systems Commissioning and Completion Requirements (C403.2.9) is a new section that introduces the added Section C408, System Commissioning. Section C408 covers commissioning of the building mechanical systems and electrical power and lighting systems, and it contains requirements that are aimed to be more process-oriented. Mechanical systems in buildings where the total mechanical equipment heating and cooling capacities are less than 600,000 Btu/h and 480,000 Btu/h, respectively, and systems serving dwelling units in hotels, motels, and boarding houses are exempt. Requirements concerning commissioning plans, system balancing, functional testing, and reports/documentation are specified, and mechanical commissioning must be completed prior to passing the final mechanical inspection. Table 1 provides brief descriptions of the individual commissioning and completion requirements within Section C408.
As the 2012 International family of codes is adopted, it is imperative that design professionals understand the changes since previous editions and the impacts they have on construction. This article touched briefly on all significant changes and points the reader to the appropriate sections of the code for further detail and context.
Andrew Klein is president of A S Klein Engineering, a professional engineering firm that represents businesses and organizations throughout the building code and standard development process. The firm provides technical committee representation, building code advocacy, and building code consulting services.