Step 3. Know the requirements of the applicable energy code
Once the applicable energy code is identified, the build community must become familiar with the specific requirements of that code. Most commercial building energy codes contain similar requirements for the following components of a commercial building:
- Building thermal envelope, including opaque envelope, fenestration, and foundations
- Heating, ventilating, and air-conditioning (HVAC) systems, including equipment and controls
- Service water heating (SWH) systems, including equipment and controls
- Power systems such as transformers and wiring
- Lighting systems, both interior and exterior, including fixtures and controls
- Other equipment such as motors and elevators
- Renewable energy systems.
Not every member of the build community has to be familiar with all the requirements in a commercial building energy code.
Commercial buildings are usually (but not always) designed by a team of practitioners representing different disciplines.
Most residential building energy codes contain requirements for the following components of a residential building:
- Building thermal envelope, including opaque envelope, fenestration, and foundations
- HVAC systems, including equipment and controls
- SWH systems, including equipment and controls
- Interior lighting systems.
The single biggest issue associated with knowing the requirements of the applicable energy code is that energy codes are relatively complex documents that undergo significant changes every 3 years at the national level. This means that practitioners responsible for knowing the requirements related to their discipline may frequently update their knowledge of the codes with which they work.
Fortunately, a number of organizations have a vested interest in helping practitioners understand the codes. These include DOE, the national model code and standard developing organizations (ICC and the American Society of Heating, Refrigerating and Air-Conditioning Engineers [ASHRAE]), the regional energy efficiency organizations (Midwest Energy Efficiency Alliance, Northwest Energy Efficiency Alliance, Northeast Energy Efficiency Partnerships, Southeast Energy Efficiency Alliance, and Southwest Energy Efficiency Project), and states and localities that adopt energy codes. There is no lack of pertinent information available on energy codes—it is the lack of time that practitioners have available to learn about codes that can be an issue.
The Resources section of this step contains links to a large number of resources that can help practitioners learn about codes. Most of these resources are focused on the entire code or standard, so practitioners need to pick and choose the sections in which they are interested.
Table 1 lists the particular sections of the most recent commercial building energy codes and standards that a practitioner might be interested in.
Table 2 provides a similar list for residential building energy codes. Note that residential building energy codes are much simpler, so Table 2 is much simpler than Table 1.
|Topic||Building Envelope||Mechanical/HVAC||Service Water Heating||Power||Lighting||Other Equipment||Additional Efficiency Package Options|
|ASHRAE Standard 90.1-2007||Section 5||Section 6||Section 7||Section 8||Section 9||Section 10||NA|
|ASHRAE Standard 90.1-2010||Section 5||Section 6||Section 7||Section 8||Section 9||Section 10||NA|
|Architect||X||X||X||X||X (daylighting)||X||X (reduced lighting power density, renewable energy)|
|Mechanical Engineer and Subcontractors||X||X||X||X||X (higher equipment efficiency)|
|Plumbing Engineer and Subcontractors||X|
|Lighting Designer and Subcontractors||X (daylighting)||X||X (reduced lighting power density)|
|Electrical Engineer and Subcontractors||X||X||X||X (renewable energy)|
|Controls Engineer and Subcontractors||X||X||X||X||X||X (renewable energy)|
|Landscaping Designer and Subcontractors||X (outdoor lighting)||X|
|Topic||Building Envelope||Systems||Electrical Power and Lighting|
An assortment of general training resources for energy codes and standards from DOE, ASHRAE, and ICC are listed under General Resources.
No matter which energy code or standard is being considered, there tend to be some specific issues that are problematic for many members of the build community. These issues include calculating loads and sizing equipment, fenestration labels, lighting controls, and mechanical requirements. These issues are discussed individually in the following paragraphs.
Load Calculations and Equipment Sizing
Energy codes typically require load calculations, equipment sizing, or both for HVAC and, to a much lesser extent, SWH equipment. Given that these two requirements are intimately related (i.e., it is impossible to do proper equipment sizing without doing load calculations, and there is little reason to do load calculations unless it is intended for equipment sizing), it is interesting to see how these topics are dealt with in various energy codes and standards. Table 3 shows the load calculation and equipment sizing requirements for HVAC and SWH equipment.
The bottom line is that there should be HVAC load calculations and sizing information for all building designs, no matter what type of building or the applicable code or standard. There should also be SWH load calculations and sizing information if ASHRAE Standard 90.1 is being used. Good design practice would indicate that all HVAC and SWH equipment should be properly sized, no matter what code or standard is being used. A specific topic brief on load calculations and equipment sizing has been prepared (Specific Issue Resource 1).
|Code or Standard||HVAC Load Calculations||HVAC Sizing||SWH Load Calculations||SWH Sizing|
|2009 IECC (residential)||Section 403.6||Implied||NA||NA|
|2012 IECC (residential)||Section 403.6||Section R403.6||NA||NA|
|ASHRAE Standard 90.1-2007||Section 6.4.2||Implied||Section 7.4.1||Implied|
|2009 IECC (commercial)||Section 503.2.1||Section 503.2.2||NA||NA|
|ASHRAE Standard 90.1-2010||Section 18.104.22.168||Implied||Section 7.4.1||Implied|
|2012 IECC (commercial)||Section C402.2.1||Section C403.2.2||NA||NA|
Energy codes typically require that fenestration (windows, doors, and skylights) has labels or certificates verifying the performance of those products. Table 4 compares the fenestration labeling requirements across various codes and standards.
The confusion that can arise over fenestration labels is that the IECC requires a label, and if that label is not available, the values in the default tables for fenestration performance must be used. In ASHRAE Standard 90.1, if a permanent nameplate is not available, then a certificate must be provided. ASHRAE Standard 90.1 also allows the use of default tables for determining fenestration performance, but those default tables do not take the place of a permanent nameplate or certificate. The IECC allows the use of a default table as a substitute for the label. Many jurisdictions allow certification from the National Fenestration Rating Council (NFRC) in lieu of labels.
While the use of the default tables may seem to be an easy and quick way to deal with the issue of equipment labels, this may not be the best option for a designer. The U-factor and solar heat gain coefficient (SHGC) values in the default table do not meet many of the prescriptive requirements found in either ASHRAE Standard 90.1 or the IECC. For example, the default U-factor and SHGC in the 2009 IECC for a double-pane, metal-framed window with clear glass are U-0.8 and SHGC-0.7. This default window would meet the U-factor requirements in only Climate Zone 1 but would not meet the SHGC requirements in any other climate zone. The default tables in both ASHRAE Standard 90.1 and the IECC have been carefully constructed to represent the worst-performing window of any given description, so any labeled or certified window that has been tested will almost invariably perform better. Best practice indicates that a building designer should have some documentation of the performance of the fenestration products installed in that building, whether that documentation is a label or sticker on the window, a permanent nameplate, or a certificate on file. To make inspection of the building easier for the code official, that documentation should be available both during plan review and on-site inspection(s).
|Code or Standard||Fenestration Product Labeling||Exceptions|
|2009 IECC (residential)||Section 303.1.3||If no label, default table may be used|
|2012 IECC (residential)||Section R303.1.3||If no label, default table may be used|
|ASHRAE Standard 90.1-2007||Section 22.214.171.124||If no permanent nameplate, may have certificate|
|2009 IECC (commercial)||Section 303.1.3||If no label, default table may be used|
|ASHRAE Standard 90.1-2010||Section 126.96.36.199||If no label, default table may be used|
|2012 IECC (commercial)||Section C303.1.3||If no label, default table may be used|
This issue is entirely a commercial building issue, as residential codes do not currently require lighting controls. There are a lot of lighting control requirements in both ASHRAE Standard 90.1 and the IECC, and that number increases with each new version of the codes. Lighting control requirements in energy codes can be summarized as:
- Use only as much lighting power as needed to provide the necessary lighting levels in the space.
- Have controls to allow the occupants to turn off or turn down lights when not needed.
- Have controls to automatically turn off or turn down the lights when not needed.
The amount of lighting power allowed to provide the necessary lighting levels in a space has gone down steadily in codes, thanks to improvements in lighting technology over the years. In terms of control requirements, there are requirements for manual switches, occupancy sensors, and automatic shutoff of lighting in most energy codes, for bi-level switching in some of those codes, and there are beginning to be requirements for daylighting controls as well in the energy codes. The lighting requirements in ASHRAE Standard 90.1 and the IECC are not identical, as shown in Table 5. It should be noted that exceptions apply in both ASHRAE Standard 90.1 and the IECC for emergency and egress lighting that may be required in other building codes.
A specific topic brief on lighting has been prepared (Specific Issue Resource 2). Other good sources of lighting control information for ASHRAE Standards 90.1-2007 and 90.1-2010 (and indirectly for the 2009 and 2012 IECC) are the ASHRAE Standard 90.1 Users’ Manuals available from ASHRAE (see General Resource 1).
|Code or Standard||2009 IECC Residential||2012 IECC Residential||ASHRAE Standard 90.1-2007||ASHRAE Standard 90.1-2010||2009 IECC Commercial||2012 IECC Commercial|
|Interior Lamp Efficacy||404.1||R404.1||NA||NA||NA||NA|
|Interior Lighting Power Density||NA||NA||188.8.131.52||184.108.40.206||505.5.1||C405.5.1|
|Automatic Lighting Shutoff||NA||NA||220.127.116.11||18.104.22.168||505.2.2.2||C405.2.2.1|
|Daylight Zone||NA||NA||NA||22.214.171.124, 126.96.36.199||505.2.2.3||C405.2.2.3|
|Specific Application Controls||NA||NA||188.8.131.52||184.108.40.206||NA||C405.2.3|
|Parking Garage Controls||NA||NA||NA||220.127.116.11||NA||NA|
|Exterior Lighting Efficacy||404.1||R404.1||9.4.4||NA||505.6.1||C405.6.1|
|Exterior Lighting Power Density||NA||NA||9.4.5||9.4.3||505.6.2||C505.6.2|
|Exterior Lighting Controls||NA||NA||18.104.22.168||22.214.171.124||505.2.4||C405.2.4|
The issues discussed here are almost entirely commercial building issues because residential codes are not as complicated as commercial codes. Mechanical requirements typically include equipment requirements and system requirements. Mechanical requirements may also cover both HVAC and SWH systems, and there may be differences between how HVAC and SWH systems are treated in the codes. (See discussion of load calculations and sizing.) As a general rule, most mechanical requirements can be summarized as:
- Size equipment
- Use efficient equipment
- Use “free-cooling” (economizers)
- Insulate pipes and ducts to avoid uncontrolled heat loss or gain in fluids
- Have controls to automatically turn equipment off or turn it down when not needed
- Have controls to avoid mixing hot and cold fluids or reheating cooling fluids.
However, these requirements tend to be expressed in multiple tables and sections throughout the code, and it can be difficult to figure out what is required. The problem is compounded by the fact that there are a lot of very complex mechanical systems used in commercial buildings, and deciding which requirements are applicable means understanding these complex systems.
One issue related to the mechanical requirements is that the efficiency of most types of mechanical equipment is regulated by the federal government rather than by energy codes (with chillers being the major exception). Designers and code officials may be lulled into complacency by the thoughts that “all equipment available from manufacturers will meet code,” which is correct except in those cases where equipment is not covered by federal legislation (e.g., chillers) or where equipment of higher-than-minimum efficiency has been proposed for use in a whole-building tradeoff or an above-code program. In these two cases, it is very important that the proper equipment efficiency be achieved.1 Not all of the products regulated by DOE are also covered in building energy codes. For example, DOE’s residential products list includes clothes washers, clothes dryers, and television sets. While these products do use energy, they are not regulated in building energy codes.
Beyond the efficiency of individual pieces of mechanical equipment, mechanical systems as a whole are also important. Mechanical systems are responsible for most of the energy used in buildings these days, so it is vital that they be designed properly, made to work properly, and inspected properly.2 To address the “made to work properly” need, codes and standards require testing, balancing, and/or commissioning of mechanical systems. A topic brief on testing, balancing, and commissioning addresses this issue (Specific Issue Resource 3).
Also addressed within the mechanical requirements is mechanical system controls. A good resource for mechanical controls requirements is BECP’s HVAC Controls Guide for Plans Examiners and Building Inspectors (Specific Issue Resource 4).
- ASHRAE Standard 90.1 User’s Manual—ANSI/ASHRAE/IESNA Standard 90.1-2007 and ASHRAE 90.1 User’s Manual ANSI/ASHRAE/IES Standard 90.1-2010—available from the ASHRAE Bookstore
- DOE Code Compliance Software
- DOE Training Materials
- DOE Building Tools Directory
- ASHRAE Standard 90.1-2010 and Standard 189.1-2011
- International Code Council Resources
- Load Calculation Topic Brief
- Lighting Topic Brief
- Testing and Commissioning Topic Brief
- HVAC Controls Guide for Plans Examiners and Building Inspectors—Resource Guide
- See a complete listing of residential products covered by DOE equipment standards rulemakings. See a similar list for commercial products.
- See Table 1.1.4 of DOE’s Building Energy Databook, for an estimate that mechanical systems (HVAC and SWH) account for 61.5% of site energy usage and 50.1% of source energy usage in buildings.