You asked for a comparison of building energy efficiency standards in California and Connecticut, particularly provisions that are found in California's standards that are not in Connecticut's standards.

SUMMARY

California and Connecticut both have extensive energy efficiency provisions as part of their state building codes. Both codes have separate requirements for residential and commercial buildings, the latter including large apartment and condominium buildings. The requirements vary by climate zones in both states. California has 16 such zones while Connecticut has three (Hartford County, the four coastal counties, and the northeast and northwest corners of the state). Both codes have efficiency standards for building envelopes (walls, ceilings, windows, etc. ). Both also have standards for mechanical equipment, including heating, air conditioning, and water heating systems.

Both states allow builders and designers to comply with the code using two approaches. The prescriptive approach has specific requirements for such things as wall and ceiling insulation. The performance approach is more complicated, but allows for more flexibility and potentially lower costs. It allows a building to be built so long as its energy consumption is no more than that of a comparable building that meets the prescriptive standards. The performance approach can be used on a component or building-wide basis. According to Paul Bette of the Department of Public Safety, which develops Connecticut's code, most residential builders use the prescriptive approach while most commercial builders use the performance approach. It appears that the performance approach is widely used for all types of buildings in California.

Connecticut has adopted the 2003 International Energy Conservation Code (IECC) for residential buildings, with minor amendments. California's residential code exceeds these standards. Connecticut has adopted the ASHRAE/IESNA 90. 1-1999 standards for commercial buildings. California's code meets or exceeds these standards. California updates its code every three years; Connecticut every three to five years.

While the codes are broadly similar, California's code goes beyond Connecticut's by:

1. being more comprehensive, e. g. , by setting lighting efficiency standards for residential buildings and “cool roof” requirements for commercial buildings;

2. having several mandatory requirements that apply whether the prescriptive or performance approach is being used;

3. giving energy savings produced during peak demand periods a higher value than savings during off-peak periods under the performance approach for commercial buildings;

4. requiring increased use of natural lighting in certain low rise commercial buildings; and

5. allowing local governments to adopt and enforce their own energy standards that are more stringent than the state standards.

On the other hand, Connecticut, but not California, allows designers and builders to use two commercial software packages to determine compliance of their designs with the code under the performance approach. Instead, California has approved the use of several state-specific packages.

Much of the information in this report on the California code is taken from manuals published by the California Energy Commission, which are available on-line at http: //www. energy. ca. gov/title24/2005standards/index. html. In addition, the Building Code Assistance Project, http: //www. bcap-energy. org/, has brief summaries of the buildings code for all 50 states.

CONNECTICUT

Scope

The Office of the State Building Inspector is responsible for reviewing, developing, adopting, and administering the State Building Code, including its energy efficiency provisions. These provisions went into effect on December 31, 2005. The code is normally revised every three to five years.

The code establishes minimum prescriptive and performance-related regulations for the design of energy-efficient buildings and structures that provide facilities or shelter for public assembly, educational, business, mercantile, institutional, storage, and residential occupancies, as well as those parts of industrial buildings designed primarily for human occupancy. The code does not apply to buildings on or eligible for the National Historical Register or designated as historic by the state.

The code addresses the design of energy-efficient building envelopes and the selection and installation of energy-efficient mechanical, service water-heating, electrical distribution and illumination systems and equipment for the effective use of energy in buildings and structures. The code has provisions to reduce light pollution, generally requiring the use of full cut-off luminaries for outdoor lighting at commercial buildings.

Residential Buildings

Designers and builders may comply with the code requirements by using the prescriptive or performance approaches. The former set specific standards for building components, such as the building envelope, which vary by building type, climate zone, and the amount of glass in the building. For example, a one or two family home in Hartford County with a 15% window to exterior wall area ratio must have R-38 insulation in ceiling, R-17 insulation in the walls, R-19 insulation in the floors, and the windows must have a U value of at least 0. 45 (the U value is the reciprocal of the R value). The requirements are somewhat lower in the four coastal counties (Fairfield, New Haven, Middlesex, and New London) and somewhat higher in Litchfield, Tolland, and Windham counties. Buildings with more extensive glazing must meet higher values. Builders and designers of residential buildings can use a simplified version of this approach, which has somewhat more conservative values. This option is available for one- and two-family homes and small apartment buildings with glazing of no more than 15% of exterior wall area and townhomes with up to 25% glazing.

In addition to the envelope standards, the building's mechanical systems must meet efficiency standards. Oil and natural gas furnaces must have an annual fuel utilization efficiency (AFUE) rating of at least 78%, oil and gas boilers must have an AFUE rating of at least 80%, and air conditioners must have a seasonal energy efficiency rating (SEER) of at 9. 7 (package systems) or 10. 0 (split systems). The standard for water heaters varies by fuel type and whether the water heater has a storage unit.

The code alternatively allows designers and builders to meet its requirements with the performance approach. Under this approach, a building or building component is acceptable if it uses no more energy than a comparable standard design building that meets the prescriptive standards. The standard design is a building that, among other things, (1) has glazing equal to 18% of the exterior wall area, (2) no skylights or awnings, and (3) U values for windows and walls that vary by the number of heating and cooling degree days in the area where the home will be built. When the proposed design is compared to the standard design, certain values such as thermostat settings are held constant. Compliance can be demonstrated on a component or total building basis.

Commercial Buildings

Designers and builders of commercial building can meet the code by complying with the ASHRAE/IESNA 90. 1 standard. This standard sets prescriptive requirements for the building envelope and mechanical systems. In addition, to the systems covered by the code's residential provisions, commercial buildings must meet energy efficiency requirements for indoor and outdoor lighting. There are also requirements for systems found in commercial buildings that are not commonly found in residential buildings, such as water chillers used in air conditioning systems.

Alternatively, a building can meet Connecticut's standards by using acceptable practices. Under this approach, a building estimated annual energy cost is compared to a comparable building that meets the state's design standards. This differs somewhat from the performance approach used for residential buildings, where the comparison is based on energy usage, rather than costs. The design standards for commercial buildings vary by the ratio of window to wall area. They also vary by the type of construction used in the building, e. g. , wood versus metal joists and trusses, among other things.

CALIFORNIA

The California Building Standards Commission is responsible for adopting, publishing, and implementing the state building code (California Code of Regulations, Title 24). Since 1989, the commission has published complete editions of Title 24 every three years. The 2005 energy efficiency standards became effective October 1, 2005. The commission has begun work on the 2008 standards.

Scope

The energy provisions of the code apply to most types of new buildings and to additions and alterations that require a building permit. In addition, replacement windows in low-rise residential buildings must comply with the code's prescriptive requirements. Under the code, multifamily residential buildings with more than three stories are subject to the commercial standards. The code does not apply to hospitals, nursing homes, temporary buildings, and prisons. It also does not generally apply to alterations of qualified historic buildings.

The commission may exempt any building from the standards if it finds that (1) substantial funds had been expended in good faith on planning, designing, or engineering the building before the adoption date of the provision or (2) compliance with the standards would be impossible without both substantial project delays and substantial increases in costs of construction.

Code Components

The code promotes energy efficiency through envelope, mechanical equipment, and lighting system measures. Certain measures are mandatory in all new construction, while builders can comply with other code provisions using the prescriptive or performance approaches.

Envelope Measures. The regulations for envelope measures establish wall, ceiling and floor insulation levels and door and window standards. Envelope measures also address the amount of windows in the building, type and shading of glass, and skylights; the thermal mass of the building (materials used that slow temperature variation within the building such as concrete, brick, and masonry); and specific air leakage controls, including weather-stripping and caulking.

The residential standards have more stringent envelope requirements than the commercial standards because homes use energy 24 hours a day and the building envelope is critical to home comfort levels. Commercial buildings generally use energy for fewer hours each day, and energy use is driven much more by these buildings' occupants and lighting systems than it is by outside temperature.

Mechanical Equipment Measures. The code addresses, among other things: space-conditioning equipment type and sizing; efficiency; and controls (such as setback thermostats), duct construction, ventilation requirements and economizers. Water heaters, plumbing equipment and swimming pool and spa heaters must also meet various efficiency requirements.

Lighting System Measures. Residential lighting measures include requirements for efficient general purpose lighting (such as fluorescent lamps) in kitchens and bathrooms. There is more emphasis on lighting in the commercial standards since it represents greater proportion of energy use. There are several mandatory measures to ensure efficient control and use of lighting. Compliance for the lighting standards is based on energy use in watts per square foot of floor area.

Mandatory Measures

For all buildings, under the prescriptive or performance compliance paths, there are mandatory measures that must always be installed. Many of these measures deal with infiltration control and lighting; others require minimum insulation levels and equipment efficiency.

The minimum mandatory levels are sometimes superseded by more stringent prescriptive requirements. For example, if mandatory measures specify R-19 ceiling insulation and the prescriptive approach specifies R-38 ceiling insulation, then R-38 must be installed. Conversely, the mandatory measures may be of a higher efficiency than permitted under the performance approach; in these instances, the higher mandatory levels must be installed. For example, a building may comply with the performance computer modeling with only R-7 insulation in a raised floor; however, if mandatory requirement for this raised floor is R-19, the R-19 must be installed under the mandatory requirements.

Prescriptive vs. Performance Approaches

Residential Buildings. The prescriptive approach offers little design flexibility but is relatively easy to use. Each individual energy component of the proposed building must meet a prescribed minimum efficiency. However, there is some flexibility for building envelope components. For example, portions of a wall need not meet the prescriptive insulation requirement as long as the walls, taken as a whole, comply.

The code provides three packages of measures under the prescriptive approach for residential buildings. One package is designed for buildings that use electric heat, while the other two apply to buildings that use other heating sources. Standard Package D is for homes that do not use electric resistance heat. It requires that heat pumps and split system air conditioners be tested to verify that (1) they have the correct refrigerant charge or field-verified that they have a thermostatic expansion valve and (2) air distribution ducts have leakage below 6%. Alternative Package D is a modification to Standard Package D that does not require field verification and diagnostic testing. The window performance and cooling system (or in some cases the heating system) efficiency is more stringent instead, in order to achieve the same level of energy savings as Standard Package D. Package C allows the use of electric resistance space heat, but increases stringency for most envelope features to make up for the additional energy that would be used by the electric heating systems. Electric water heating may also be used with Package C if the water heater is located inside the building and 25% of the water heating is provided by solar or a wood stove boiler.

The performance approach is more complicated but offers considerable design flexibility. The performance approach requires an approved computer software program that models a proposed building, determines its allowed energy budget, calculates its projected energy use, and determines when it complies with the budget. The main prescriptive package (Package D) sets the stringency of the standards for the performance approach. Compliance options under the performance approach include such things as window orientation, shading, thermal mass, zonal control, and house configuration. According to the commission's manual, this approach is popular with production home builders because it is flexible and provides a way to find the most cost-effective solution for complying with the code.

Commercial Buildings. The prescriptive envelope requirements are determined on a component or overall envelope basis. The stringency of the envelope requirements varies according to climate zone and how the building will be used. The prescriptive mechanical requirements specify hardware features and design procedures that must be followed. The prescriptive indoor lighting requirements are determined by the Complete Building, Area Category, or Tailored methods. The allowed lighting under the standards varies according to the requirements of the particular building occupancy or task requirements. The prescriptive outdoor lighting requirements are determined by lighting application type (general

and specific) and the lighting zone for each application. In addition, lighting power limits (or alternative equipment efficiency requirements) apply to externally and internally illuminated signs used either indoors or outdoors.

The performance approach requires that the annual time-dependent values (TDV) of energy use be calculated for the proposed house and compared to the allowed energy budget. TDV energy is the “currency” for the performance approach. It takes into account both the type of energy that is used (electricity, gas, or propane), and when it is used. Energy saved during periods when California is likely to have a statewide system peak is worth more than energy saved at times when supply exceeds demand.

The performance approach allows a wider variety of design strategies and provides greater flexibility than the prescriptive approach. It is based on an energy simulation model of the building. The standards specify the method for determining an energy budget for the building. This energy budget represents the upper limit of energy use allowed for that particular building. The designer is permitted to trade off different aspects of the building design, one against the other, when permit applications for more than one component are submitted at the same time. As long as total energy use considering all installed components does not exceed the allowed budget, the tradeoff is acceptable.

Three basic steps are involved under this approach:

1. design the building with energy efficiency measures that are expected to be sufficient to meet the energy budget;

2. demonstrate that the building complies with the mandatory measures; and

3. using an approved calculation method, model the energy consumption of the building using the proposed features to create the proposed energy budget. The model will also automatically calculate the allowed energy budget for the proposed building.

If the proposed energy budget is no greater than the allowed energy budget, the building complies.

Features Not Included in the Connecticut Code

One recent change in the California code has been the use of the time-dependent values (TDV) approach. TDV energy places a higher value on energy savings greater during periods of likely peak demand, such as hot summer weekday afternoons, and values energy savings less during off peak periods. TDV thus gives more credit to measures such as daylighting and thermal energy storage that are more effective during peak periods.

For residential buildings, the code requires fluorescent or other high efficacy lighting in kitchens; high efficacy lighting or motion sensor in bathrooms, utility rooms, garages, laundry rooms; high efficacy or combined photo sensor/motion sensor for exterior lights; and high efficacy or dimmer in other lighting. It requires that the leakage from ducts be tested in the field. It also encourages third-party field verification of other efficiency measures, including compliance credit for field-verified high quality installation of insulation.

For new residential buildings and certain residential alterations using prescriptive approach, the code limits the glassed area to 20% of the floor area that is heated or cooled. It limits the west facing glass in new buildings in zones where air conditioning is the primary energy use to 5% of the conditioned floor areas. Buildings using the performance approach get credits for installing highly efficient air conditioners, high quality insulation installation, properly sized air conditioners, efficient air conditioner fan motors, and ducts buried in attic insulation

Commercial buildings using the prescriptive approach must include “cool roofs” in all flat and low slope roofs. Cool roofs have light-colored surfaces that reflect most of the light hitting them, thereby reducing demands on air conditioners. This requirement also applies to roof replacements for existing buildings. The prescriptive standards also require that skylights be installed in the top story of large, open spaces (spaces larger than 25,000 square feet with ceilings higher than 15 feet) and that they have controls to shut off electric lights when outdoor light is sufficient.

Unlike Connecticut, California allows local governments to adopt and enforce their own energy standards for new buildings, additions, alterations, and repairs, so long as the State Energy Commission finds that they are at least as stringent as the state standards. The local standards may require compliance with the state standards before their effective date, require additional energy conservation measures, or set more stringent energy budgets.

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