CalGreen: California's Building Code

May 01, 2011
May/June 2011
A version of this article appears in the May/June 2011 issue of Home Energy Magazine.
Click here to read more articles about Codes and Standards

At the Passive House conference held in Portland, Oregon, last fall, one European Passive House expert stated that the best way globally to reduce humanity’s carbon footprint worldwide is to legislate stricter building codes. That approach has met with success in parts of Europe. Individual and local efforts are all well and good, and should be commended, but states and countries have to step up and make sustainable building mandatory. Here in the United States, we don’t have a national green-building code. There are various local, regional, state, and federal initiatives that encourage or require some degree of sustainable building, but no mandatory national code.

Steve Mann is a HERS rater, Green Point rater, LEED AP, Energy Analyst, serial remodeler, and longtime software engineer. (April Wise Photos)

As of January 1, 2011, California requires adherence to the 2010 California Green Building Standards Code, affectionately known as CalGreen. Championed by former Governor Arnold Schwarzenegger, CalGreen applies to new residential and commercial construction. It contains a set of mandatory provisions, and two voluntary tiers that can be adopted in whole or in part by local code jurisdictions. The optional tiers are indicators of what will most likely become mandatory measures in future versions of the code.

CalGreen is a separate code body from the current California Energy Code, officially titled 2008 Building Energy Efficiency Standards (commonly referred to as Title 24), but the two are complementary. When CalGreen refers to energy-efficiency matters, it typically does so in terms of Title 24 requirements, and defers to the Energy Efficiency Standards. However, there are specific CalGreen provisions that go above and beyond Title 24 requirements.

The Big Picture

Residential CalGreen, the focus of this article, contains approximately 90 provisions, divided into five categories: Planning and Design, Energy Efficiency, Water Efficiency and Conservation, Material Conservation and Resource Efficiency, and Environmental Quality. Twenty-five of the provisions are mandatory for all new residential construction. The remainder fall into two optional tiers (see Tables 1 and 2). Each tier includes some prerequisites that must be met. Each tier also requires that a project include a certain number of optional provisions. For instance, Planning and Design has two mandatory measures and 14 electives. In order to satisfy that category’s Tier I requirements, you have to meet the mandatory measures and include two optional provisions. The best way to get an understanding of the overall code is to look at Appendix A4 in Section A4.602 of the regulations. It has a concise table of all the requirements, with descriptions noting which are mandatory for each tier.

The tier structure, although useful, is somewhat arbitrary. Local code jurisdictions can require that all projects meet the requirements for one of the tiers (the simplest approach), or they can cherry-pick whatever they want, such as ten items from Tier I and five items from Tier II. They can enact requirements that are even more stringent than CalGreen. There are also provisions for “Innovative Concepts and Local Environmental Conditions” in each category.

Currently, California’s municipalities are reviewing CalGreen and deciding what portions they want to adopt. Clearly, there is a lot of flexibility beyond the basic mandatory measures. Builders, home performance professionals, and energy consultants are worrying that it’s going to be difficult to track what might be wildly varying requirements in each district. The California Energy Commission has stated that it plans on publishing a database of jurisdictional CalGreen variations, but that will probably take some time to develop.

Mandatory Requirements

The CalGreen mandatory requirements are, for the most part, straightforward and not too onerous (with a few exceptions). Many of them are already required by local jurisdictions, or reflect industry best practices or just plain common sense. Table 3 is a summary of the mandatory requirements.

In the Planning and Design category, you have to develop a plan to manage storm water drainage during construction, and a postconstruction surface water management plan. Most municipalities already require both of these, and many rural jurisdictions require erosion control plans as well. To meet the Energy Efficiency requirements, you only have to comply with the Title 24 baseline code provisions. CalGreen explicitly states that its intent is to encourage all new residential buildings to be at least 15% more efficient than Title 24, but it’s not required. The Water Efficiency category requires you to reduce indoor water usage by at least 20% by meeting specific fixture flow rates or doing a simple water use calculation. The flow rates are reasonable—2 gpm for the total of all showerheads in a stall, 1.5 gpm for lavatory faucets, 1.8 gpm for kitchen faucets, and 1.28 gallons for toilets. Irrigation systems require weather- or soil moisture-based controllers.

Material Conservation provisions require sealing all building envelope penetrations. Exterior-plate penetrations are supposed to be sealed with a cementitious material to deter rodents. In addition, a minimum of 50% of construction waste has to be recycled or salvaged. If the local jurisdiction doesn’t have a waste management ordinance, you have to develop a waste management plan and submit it to the enforcing agency. Finally, you have to provide an operations and maintenance manual to the building owner. CalGreen has a list of specific topics that are supposed to be included in that manual.

With 14 mandatory measures, the Environmental Quality category is the toughest to meet. Gas fireplaces must be closed combustion; wood fireplaces must meet expanded polystyrene (EPS) Phase II emission standards. Duct openings have to be sealed during construction to avoid contamination. Adhesives, sealants, paints, carpets, resilient flooring, and interior finish materials like medium-density fiberboard (MDF) and particleboard all have to meet fairly stringent VOC standards. Framing must have moisture content less than 20% before it can be covered. Bathroom fans must be Energy Star labeled, vent to the exterior, and be controlled by a humidistat unless they are part of a whole-house ventilation system. Whole-house exhaust fans must have covers or louvers that are insulated to at least R-4.2. HVAC systems must be designed using ACCA Manual J, D, and S methodologies or equivalents.

Only one of the mandatory requirements requires onerous documentation—the building operations and maintenance manual. It’s my experience that the highest-quality builders of, typically, custom homes, always assemble an O&M manual for their homeowners. This will be a burden for production builders and builders of other lower-end structures, at least the first time around. It should be easy to develop a template that can be readily adapted to multiple projects without too much work. Although the construction waste requirement seems like a pain, all the jurisdictions I work within, spanning five counties, already have a 50% minimum waste diversion requirement and landfill documentation that makes it pretty easy to track. It’s unlikely that anyone will have to develop their own unique waste diversion plan. If so, CalGreen includes a sample plan and associated work sheets.

The requirement that I think will irritate some folks is that HVAC systems have to be designed using ACCA Manual J, D, and S. The only place I see designed mechanical systems is on some high-end houses. Most HVAC contractors do what are called field design systems, a great euphemism for “seat of the pants.” They don’t know or care about ACCA, they don’t have the certified software, and they don’t have the time or interest to do a formal design. It will be interesting to see how that part of the code evolves.

Tier I

Tier I is the lower of the two voluntary CalGreen code levels. The tier system permeates many of California’s energy-related mandates. Tier I is defined by the investor-owned utilities, the California Energy Commission, and other parties as 15% over the current Title 24, which is updated approximately every three years. Tier I is the minimum requirement to participate in many of the utility incentive programs. It’s the baseline efficiency for Energy Star certification. It shows up in a variety of ways in other parts of the energy sector.

Table 1. CalGreen Tier I Prerequisites

CalGreen calls its first voluntary level Tier I, but it means much more than just being 15% better than Title 24. In order to achieve Cal Green Tier I performance, you also have to meet additional requirements, summarized in Table 1.

In Planning and Design, you have to stockpile, protect, and reuse displaced topsoil. At least 20% of the project hardscapes have to be permeable surfaces, and roof coverings must be certified cool-roof material. As I’ve already mentioned, in Energy Efficiency, you have to exceed Title 24 by 15% as determined by a modeling calculation. That can involve improvements to many aspects of the building, including the envelope, shell leakage, insulation levels, mechanical equipment efficiencies, passive-solar design, and more (renewables are currently excluded from those calculations). To meet Tier I Water Efficiency thresholds, kitchen faucets cannot exceed 1.5 gpm, and landscape designs have to reduce the use of potable water by 35% (that’s a slight simplification of the actual calculation). In the Material Conservation category, you have to reduce concrete use by at least 20%, with additives like fly ash, and use at least 10% recycled materials, by cost, with postconsumer content weighed more heavily than postindustrial content. You have to reduce construction waste by 65%. Finally, in Environmental Quality, at least 80% of installed resilient flooring and all insulation must meet specific VOC levels.

Once you meet the Tier I prerequisites, you still have to select a certain number of electives in each category (the exact numbers are shown in Table 4). The electives cover a wide range of options. For instance, Planning and Design options include disassembling and reusing or recycling existing buildings, passive-solar orientation, and limiting turf. Energy Efficiency electives include radiant barriers, west- and south-facing window shading, blower door and duct testing, an HVAC commissioning plan, mechanical equipment efficiencies, renewables, and much more. Many of the efficiency electives affect a project’s Title 24 calculation, letting you kill two birds with one stone. For instance, a good passive-solar design can radically improve your Title 24 score. The same is true for duct and blower door testing. By selecting these types of measures, you can satisfy both the Tier I percentage threshold and the Energy Efficiency elective requirements. You can meet the Water Efficiency elective requirements by reducing potable irrigation water use, rainwater capture, and graywater and recycled-water systems. Material Conservation electives include a variety of framing efficiency measures, low-maintenance materials, and moisture management measures. Environmental Quality electives are limited to meeting stricter formaldehyde requirements, greater than MERV 6 filters, and having no direct-vent appliances in conditioned space.

Table 2. CalGreen Tier II Prerequisites

Tier II

Tier II takes selected Tier I electives and makes them mandatory. In addition, Tier II also requires more electives than Tier I, from what is now a smaller pool, since some former electives are now prerequisites. Some of the Tier II requirements, summarized in Table 2, are similar to Tier I with higher thresholds; others are brand-new. The CalGreen reference guide warns that it’s difficult to achieve Tier II and suggests that local jurisdictions think carefully before making it mandatory.

In Planning and Design, in order to reach Tier II, you have to protect the topsoil (as required for Tier I), plus delineate the construction area with fencing or flags to protect it from damage by machinery and other construction activities. You also have to have at least 30% permeable hardscape (instead of 20% for Tier I) and cool-roof specifications that are more stringent than those for Tier I. For Energy Efficiency, you have to exceed Title 24’s baseline by 30% instead of 15%. In the Water Efficiency category, you have to meet the Tier I kitchen faucet 1.5 gpm requirement, plus install an Energy Star dishwasher that uses no more than 5.8 gallons per cycle. For outdoor water use, you have to reduce potable water use by at least 40% instead of 35%. Tier II Material Conservation requires that you reduce cement use by 25% instead of 20%, increase recycled material use by 15% by value, and reduce construction waste by at least 75% instead of Tier I’s 65%. For Environmental Quality, 90% of the resilient flooring must be low VOC, and insulation must comply with Collaborative for High Performance Schools (CHPS) standards and have no added formaldehyde.

The Tier II electives are all the code provisions that remain after meeting all the mandatory items and the Tier I and Tier II prerequisites. In order to complete a Tier II certification, you need to include the number of electives shown in Table 4: Planning and Design (4), Energy Efficiency (6), Water Efficiency (2), Material Conservation (4), and Environmental Quality (2). If your project manages to do all these things, you should have a pretty darn green building.

Table 3. CalGreen Mandatory Requirements


Overall, CalGreen seems to be both relatively green and flexible. Code jurisdictions can craft programs to suit their local requirements, and builders have multiple ways to comply without running up too many heavy expenses. Interestingly, many of the CalGreen provisions are similar to LEED for Homes provisions but not as stringent. Both systems track compliance with a prescriptive checklist and performance-based energy efficiency thresholds. What’s missing, in the Energy Efficiency category for both systems, is a requirement to track a building’s energy use after occupancy. This is a fairly recent, and not unfair, criticism of the various LEED rating systems. There’s no point in building better buildings if the only proof we have of their quality is the output from a modeling program or items on a prescriptive checklist.

Some of the CalGreen documentation requirements may be difficult to meet, but most of the provisions with documentation requirements are elective. Many of them are also a bit vague, leaving the specific requirements up to local enforcement officials. Likewise, the enforcement and compliance guidelines are vague. It is pretty much left up to each jurisdiction to decide how it wants to enforce CalGreen. The regulations suggest that HERS raters or other special inspectors who are “qualified and able to demonstrate competency” may be used, but they’re not required. There are no HERS rater requirements, however, even for elective provisions such as duct testing, which can only be done by a HERS rater if the duct test is being used for Title 24 compliance credit. The overlap between CalGreen and HERS testing could be tightened up.

CalGreen states that HVAC installers should be properly trained and certified, but it doesn’t clearly and specifically define what that means. “Nationally or regionally recognized training or certification programs” are acceptable. In addition “uncertified persons may perform HVAC installations when under the direct supervision and responsibility of a person trained and certified to install HVAC systems or contractor licensed to install HVAC systems.” That leaves a certain amount of additional wiggle room in the HVAC certification requirement, guaranteeing that there will be no significant change.

Table 4. CalGreen Summary

Enforcement will probably be an issue for many months. It’s a well-known fact that enforcement of the current HERS regulations is spotty at best, and a downright failure much of the time. CalGreen just adds another layer of compliance that, based on the history of California’s HERS requirements, will be difficult to enforce. Code officials will have to be trained, and then jurisdictions will have to find the resources to enforce the code, if they are motivated to do so. It will be interesting to see how this all plays out.

There will be additional confusion and complexity because the state is encouraging each jurisdiction to develop its own variation on the straightforward Tier I and Tier II definitions. In the past several years, various counties and cities have adopted their own green-building codes, complicating the marketplace. CalGreen was an opportunity to address that problem by simplifying statewide requirements. It appears it will end up doing just the opposite—increasing complexity by introducing even more local green-building codes.

These issues aside, and forgetting for the moment that CalGreen does not address existing buildings (California’s HERS II program, still being tweaked as of this writing, is supposed to do that), it’s a step in the right direction. There’s a saying: As California goes, so goes the rest of the country. CalGreen may be a vehicle that helps propel other states to adopt tougher green-building codes. In our wildest dreams, it could even be the legislation that persuades the federal government to adopt a strict national green-building code. Wouldn’t that be something?

learn more

The CALGreen code and guide are available online at
Steve Mann can be reached at

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