zero net energy: getting there through code · 2017. 8. 1. · zero net energy: getting there...

Gregory C Mahoney CBO, LEED AP Chief Building Official City of Davis

Zero Net Energy: Getting There Through Code

Introduction Gregory C Mahoney, CBO LEED AP Chief Building Official City of Davis [email protected] (530) 757-5655

mailto:[email protected]

Certificate of Completion

Everyone attending today’s workshop will receive a certificate of completion, by e-mail, from Green Technology for 3 hours of continuing education credit.

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Continuing Education Green Technology is a Registered Provider with The American Institute of Architects Continuing Education Systems (AIA/CES). Credits earned on completion of this program will be reported to AIA/CES for AIA members. Certificates of Completion for both AIA members and non-AIA members will be e-mailed.

This program is registered with AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material or construction or any method or manner of handling, using, distributing or dealing in any material or product.

Questions related to specific materials, methods, and services will be addressed at the conclusion of this presentation.

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Course Description This course is designed for those interested in Zero Net Energy (ZNE) Buildings. We will discuss what it means to be Zero Net Energy and how definitions of ZNE vary. As California moves towards ZNE by 2020 for residential structures we will discuss the process and hurdles to making ZNE the standard for the state. Some local jurisdictions are adopting ZNE early. This course will cover how code required ZNE differs from other structures considered to be ZNE. Many of the recurring questions surrounding ZNE will be discussed such as: Is ZNE cost effective? How do we get to ZNE? Why is California requiring ZNE? How do you make existing buildings ZNE? The course will examine ZNE from a code perspective and examine strategies to achieve ZNE in new and existing buildings

Learning Outcomes Understand the varying definitions of ZNE. Explain how and why the California Energy

Commission uses Time Dependent Value as a metric.

Discuss the balance of conservation/efficiency and on-site power generation.

Examine site considerations when designing a ZNE structure.

Discuss varying strategies to achieve Zero Net Energy in new and existing residential structures

Rosenthal Curve: Per Capita Electricity Consumption

16 Climate Zones in CA Micro climates within

the climate zones Energy Design Rating

(EDR) of Zero can be challenging depending on climate zone

CEC’s 7 Core Responsibilities Advancing State Energy Policy Achieving Energy Efficiency Certifying Thermal Power Plants Investing in Energy Innovation Transforming Transportation Developing Renewable Energy Preparing for Energy Emergencies

2016 Residential Energy Savings

Overall, 28% more efficient than 2013 Standards

Electric savings = 345 GWHs

Demand Reduction = 115 MW

Gas Savings = 31 Mtherms

Monthly life cycle cost of $11 with savings of $31 for “typical” home (statewide)

Summary of Major Changes Solar ready zone exceptions

revised

High efficacy lighting

New JA8 requirements

High Performance Attics (HPA)

Insulation required at ceiling and at the roof

High Performance Walls (HPW)

Maximum allowed U-factor lowered

Instantaneous water heaters

Baseline for prescriptive and performance compliance

2016 Nonresidential Energy Savings

Overall, 5% more efficient than 2013 Standards

Electric Savings = 192 GWHs

Demand Reduction = 80 MW

Gas Savings = (0.9) Mtherms

Summary of Major Changes Equipment efficiencies

Minimum reqs. increased

Envelope U-factors Maximum values lowered

Indoor and outdoor lighting Power allowances reduced

Indoor lighting alterations

HVAC door and window interlocks New sensor reqs. to turn

HVAC off

Direct digital controls

Covered Processes New reqs. for elevators and

escalators/moving walkways

What is ZNE? Zero Site Energy? Zero Source Energy? Zero Energy Bills? Zero Emissions? California Energy

Commission Definition?

What is Zero Site Energy? The site energy for a building is all of the energy used in the building: plug loads lighting loads all equipment power Zero Site Energy is when all of the site energy is offset by renewable energy either on or off site. The amount shown on your energy bill.

What is Zero Source Energy? Source energy includes the site energy plus all of the energy used to provide and distribute the site energy. Source energy is sub-divided into two major components: Primary energy is the raw material that is consumed in order to create the power. Secondary energy is the power that enters the distribution system.

Energy Flow Chart, 2015

Site vs. Source Energy Utility Supplied Electricity Utility Supplied Gas Energy that is purchased from the electrical grid typically has a site-to-source ratio of around 3.3

Natural gas provides a site-to-source ratio of approximately 1.1, meaning that there are with very minor losses along the way.

Zero Energy Bills The common understanding or misunderstanding… That a ZNE house will have “zero” utility bills.

ZNE Definition: The 2015 IEPR Vision

A ZNE Code Building meets an Energy Use Intensity value designated in the Building Energy Efficiency Standards by building type and climate zone.

These buildings incorporate best practices for highly efficient buildings.

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ZNE Definition: The 2015 Integrated Energy Policy Report (IEPR) Vision

A ZNE Code Building is one where the value of the net amount of energy produced by on-site renewable energy resources is equal to the value of the energy consumed annually by the building, measured using the California Energy Commission’s Time Dependent Valuation metric.

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Time Dependent Value (TDV) What is Time Dependent Value (TDV) of

Energy? TDV is a Time of Use “rate” or “value curve”

for the State of California The TDV values energy used differently based

on the hour of the year to reflect the cost: To consumers To the utility system To society

Time Dependent Value (TDV) The concept behind TDV is that energy efficiency measure savings should be valued differently depending on which hours of the year the savings occur, to better reflect the actual costs of energy to consumers, to the utility system, and to society. The TDV method encourages building designers to design buildings that perform better during periods of high energy cost.

Time Dependent Value (TDV) TDV is a flexible tool with values that vary: By type utility (electricity

vs. natural gas vs. propane)

By location – reflecting differences in costs driven by climate conditions

By type of construction – residential vs. nonresidential

Hourly TDV factors are correlated with the statewide weather files

Time Dependent Value (TDV) TDV calculation inputs include: Utility cost of

generation (electricity and natural gas)

Transmission and distribution costs

Emissions and environmental costs

Peak capacity costs Fixed annual utility

costs (taxes, metering, billing, etc.)

Why ZNE? AB 32: (2008) Reach 1990 levels of greenhouse gases by 2020

SB350: (2015) Reach 40% reduction of 1990 levels of greenhouse

gases by 2030. Reach 80% reduction of 1990 levels of greenhouse

gases by 2050. Increases California’s renewable electricity

procurement goal from 33 percent by 2020 to 50 percent by 2030.

Requires the state to double statewide energy efficiency savings in electricity and natural gas end uses by 2030.

SB 350

CEC Objective

How Do We Get to ZNE

(Note the last design

strategy)

ZNE Buildings In the U.S., there are nearly 6,800 net-zero housing units (including apartments and single-family homes) across 3,339 buildings. The Zero-Energy Coalition defines zero energy buildings as those that produce as much renewable energy as they consume, or could do so with slight modifications. 46% in California

ZNE Renovations

PV Becoming more affordable

The Residential New Construction Zero Net Energy (ZNE) Action Plan

The Action Plan is designed to achieve the California Long-term Energy Efficiency Strategic Plan’s (CEESP) goal to have 100% of new homes achieve ZNE beginning in 2020. The Action Plan provides a foundation for the development of : Robust and self-sustaining

ZNE market for new homes Supports future codes and

standards for ZNE Inspires voluntary actions

to meet California’s goal


To develop the Action Plan, a comprehensive stakeholder outreach process was employed. Stakeholder engagement was to: Ensure feasibility Stimulate independent

action Provide certainty Understanding of the

ZNE market


The Action Plan is focused on new residential construction, including single-family and low-rise multifamily (3 stories or less) buildings, as well as low and moderate income housing within these categories.

Demand and Awareness Demand and awareness is one of the key goals for the plan. There is a need to promote the benefits of zero net energy among: potential homeowners housing industry real estate professionals financial community developers building trades

organizations

Technical Training & Education A robust and well trained industry is essential to be able to implement and adapt to the technological innovations and integrated business strategies that are required to effectively meet the ZNE goals. We need to develop a well-informed support industry including: building inspectors financial and real estate

professionals building trades other industries central to the

advancement of ZNE.

Future Infrastructure An essential requirement for mainstream ZNE is a grid and infrastructure that can effectively manage distributed generation energy.


A planning website was launched to share information about the plan, solicit case studies, and share documents and information about relevant events: www.CaliforniaZNEhomes.com

California Energy Commission Objectives 1. All new residential construction in California

will be zero net energy or equivalent to zero net energy by 2020;

2. All new commercial construction in California will be zero net energy or equivalent to zero net energy by 2030;

Equivalency allows goal to be applicable to all buildings –even those unable to produce all net energy needs on site.

Equivalency builds on Title 24 concept of prescriptive standard and a performance calculation that results in equivalent energy consumption.

“50 percent of existing buildings will be equivalent to

California Energy Commission Objectives

For a home or low-rise dwelling unit, ZNE is achieved by demonstrating a California Whole-House Home Energy Rating of zero or less

Not Just The Building: occupant behavior, plug loads etc.

ZNE definition based upon building energy usage

i.e. does not include embedded energy in materials or water, or transportation energy (though these are important)

Building energy usage includes plug loads 54% of residential energy consumption

Indicates the importance of appliance standards –ZNE target not just a Title 24 issue

Rating tools must consider installed appliances or accurate defaults for appliance usage

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The ZNE Challenge – Load Harmonization

PV Load Harmonization Solar PV peak does not offset utility peak – PV output drops off significantly after 3 PM, while the utility-grid peak is around 6 PM or later

This results in significant PV overgeneration in mid-day when the demand is relatively low, especially in milder spring and autumn months.

Teaching the “Duck” to Fly

Lazar, J. (2016). Teaching the “Duck” to Fly, Second Edition. Montpelier, VT: The Regulatory Assistance Project.

The “Duck” Curve




The utility’s role has been to procure a least-cost mix of baseload, intermediate, and peaking power plants to serve a predictable load shape. Today, utilities have to balance a combination of variable generation power sources to meet the peaks in the load.



Over time, as more solar and wind energy are added to the grid, the “net load” to be serviced resembles a duck. The duck’s belly sags in the middle of the solar day when solar generation is highest. The head is the load to be served in the early evening after the sun goes down. The neck is the transition between peak PV production and peak demand without PV production.

The “Duck” Curve Strategy 1. Target energy efficiency to the hours when load ramps up Strategy 2. Acquire and deploy peak-oriented renewable resources Strategy 3. Manage water and wastewater pumping loads Strategy 4. Control electric water heaters to reduce peak demand Strategy 5. Convert commercial AC to ice or chilled-water storage Strategy 6. Rate design: focus utility prices on the “ramping hours” Strategy 7. Deploy electrical energy storage in targeted locations Strategy 8. Implement aggressive demand-response


Strategy 1 Addresses the period when office building loads continue, while residential loads increase as residents return from school and work. People come home, turn on televisions, start cooking, and, in the winter, use significant amounts of lighting. This late afternoon convergence of residential and commercial loads causes system peaks on most utility systems. Residential lighting Air conditioning Water heating Office building lighting controls


Strategy 2


Acquire wind, solar, or hydro resources that have favorable hourly production. Modify the dispatch protocol for existing hydro resources.

Strategy 3


Control water and wastewater pumps to operate during periods of low existing load or high solar output, curtailing pumping load during ramping hours.

Strategy 4


Control electric water heaters to increase electricity usage during night hours and mid-solar-day hours, and decrease usage during morning and evening peak demand periods.

Strategy 5


Commercial air conditioning converted to ice storage or chilled-water storage. Compressors and chillers operated during the solar day and at night.

Strategy 6


Modify rate design to focus pricing on the most crucial hours. Time of use rates replace flat rates. Avoid high fixed charges that reduce customer incentive to control usage levels.

Strategy 7


Identify locations where electricity storage, including batteries, can provide more than one function. Deploy storage to reduce the investment needed for transmission and distribution, and to provide storage of energy from renewable resources.

Strategy 8


Deploy demand-response programs that shave load during critical hours of the year, only on days when system stress is severe.

Strategy 9


Import power from other regions with different peaking periods when it is available; export power to these regions when it is economic to do so.

Strategy 10


Retire older coal, natural gas, and nuclear power plants that cannot be cost-effectively maintained and operated in the current power system. high fixed costs limited flexibility to ramp up

and down. Replace with a mix of renewable resources, flexible (mostly natural gas) resources, and storage, so the system can absorb increases.

Orientation Considerations This home gets most of its space heating from the passive solar design. The solar thermal system supplies both domestic hot water and a secondary radiant floor heating system. PV systems require proper orientation for maximize effectiveness.

Orientation Considerations In order to minimize energy use, efficient building design takes advantage of: Site Climate Materials

Orientation Considerations A well-designed home Reduces heating and

cooling loads through energy-efficiency strategies and design

Meets those reduced loads in whole or part with solar energy

Avoids oversizing south-facing glass

Properly shade south-facing glass to prevent overheating and increased cooling loads

Site Selection A portion of the south side of the building should have an unobstructed “view” of the sun. The Solar Rights Act was created in 1978. The law includes

protections to allow consumers access to sunlight

Limits the ability of homeowner associations (HOA) and local governments from preventing installation of

Village Homes, Davis CA Village Homes is a seventy-

acre subdivision located in Davis, California.

It was designed to encourage both the development of a sense of community and the conservation of energy and natural resources.

Construction on the neighborhood began in the fall of 1975

The completed development includes 225 homes and 20 apartment units.

Village Homes, Davis CA Orientation All streets run east-west

and all lots are oriented north-south.

This orientation helps the houses with passive solar designs make full use of the sun's energy.

Solar thermal systems and appropriately sized and located windows were part of the design to take advantage of orientation.

Efficiency & Conservation vs. Renewables Achieving ZNE requires a combination of energy efficiency and renewable energy production. First step is energy

efficiency and conservation.

Then renewables

Efficiency vs. Renewables Reduce the amount of energy

a home uses through : • efficient envelope design • day lighting • efficient lighting • efficient HVAC design and

install Optimize the way the building

actually operates and how people use it, including management of plugged-in devices and system controls

Install renewable generation on-site to meet the remaining energy needs of the building.

ZNE Stats Early adopters’ willingness to pay for ZNE Builders reported incremental cost to build

ZNE about 5-15% Most builders think owners not willing to pay

more Owners self-reported willingness to pay 5-

10% more for their next home to be ZNE-type

Appraisers: Suggest 5-15% more for a ZNE-type home

U.S. homes with PV sold for about $15K more for typical system (LBNL 2015)

CA homes with green label sold for 9% more than unlabeled homes

The Value of Green Labels in the California Housing Market Researchers conducted an analysis of 1.6 million homes sold in California between 2007and 2012, in order to isolate the added value of green home labels. Labels include: Energy Star LEED for Homes Green Point Rated

Reach Codes Approved and Pending

Reach Codes Approved City of Palo Alto 10% compliance margin or 20% with min 5kW PV system

City of San Francisco PV Solar Thermal City of San Mateo Cool roofs PV

Reach Codes Approved City of Novato 15% compliance margin for single-family and

multifamily new construction.

City of Mill Valley 15% compliance margin for single-family and 10% for

multifamily new construction.

City of Fremont PV LED for outdoor lighting

Reach Codes Approved County of Marin Green Point Rated City of Brisbane Cool Roof PV

City of Healdsburg (CALGreen) Tier I

ZNE Reach Code Approved City of Santa Monica PV system with a minimum total wattage 1.5

times the square footage of the dwelling or a total wattage that will offset 75 - 100 percent of the Time Dependent Valuation energy budget. Note: This amount of solar PV is most likely

insufficient to reach the Energy Design Rating (EDR) of Zero.

An additional local ordinance seeking concurrent approval (15% compliance margin) and achieve an EDR of Zero will take precedence, if approved.

Is It Cost Effective? The Warren-Alquist Act established the Energy

Commission in 1974. One of those responsibilities is to promote energy

efficiency. The Act requires the Energy Commission to

adopt cost effective building energy efficiency standards.

The cost effectiveness requirement of the Act has allowed the Energy Commission to be aggressive in developing energy efficiency standards for buildings while ensuring those regulations do not become fiscally burdensome to Californians.

Cost Effectiveness Study The California Building Energy Efficiency Standards Title 24, Part 6 (Title 24) (CEC, 2016b) is maintained and updated every three years by two state agencies, the California Energy Commission (CEC) and the Building Standards Commission (BSC).

Cost Effectiveness Study Local jurisdictions must demonstrate that the requirements of the proposed ordinance are cost effective and do not result in buildings consuming more energy than is permitted by Title 24. The jurisdiction must obtain approval from the CEC and file the ordinance with the BSC for the ordinance to be legally enforceable.

Is It Cost Effective? The TDV uses statewide average rate for electricity, natural gas, and propane to maintain similar stringency and common construction practices statewide. The overall stringency of the code is based on statewide average results.

Cost Effectiveness Study CA Statewide Codes and Standards Program Title 24, Part 11 Local Energy Efficiency Ordinances CALGreen Cost Effectiveness Study Prepared for: Marshall Hunt Codes and Standards Program Pacific Gas and Electric Company Prepared by: Davis Energy Group, Inc. Enercomp, Inc. Misti Bruceri & Associates,

LLC

Is It Cost Effective? The cost effectiveness for the Building Energy Efficiency Standard TDVs are based on long-term (15- and 30-year) forecasts. Reflect existing energy trends State policies The timeframe of the economic analysis used in the 2019 TDVs spans the years 2020 to 2049 for the 30-year analysis and 2020 to 2034 for the 15-year analysis.

Is It Cost Effective? The analysis includes scenarios of compliance packages options and cost effectiveness analysis for all sixteen California climate zones that is based on the 2016 Standards.

Is It Cost Effective? Four levels of building energy performance were examined: 1. CALGreen Tier 1- Exceeding the minimum

requirements by at least 15% . 2. CALGreen Tier 2- Exceeding minimum

requirement by at least 30%. 3. Energy Design Rating of Zero -Meeting minimum

Title 24, Part 6 efficiency performance targets plus on-site renewable energy generation sufficient to achieve TDV-Zero.

4. PV Plus - Meeting minimum Title 24, Part 6 efficiency performance targets plus on-site renewable energy generation sized to offset 80% of the total TDV loads.

Methodology and Assumptions The CEC defines building prototypes which it uses to evaluate the cost-effectiveness of proposed changes to Title 24 requirements. There are two single family prototypes and one multifamily prototype, all three of which are used in this analysis in development of the code efficiency packages.

Methodology and Assumptions Each prototype building has the following features: Slab-on-grade foundation Vented attic. High performance attic in climates

where prescriptively assigned (CZ 4, 8-16) with insulation installed below roof deck. Refer to Table 150.1-A in Appendix A.

Ductwork located in the attic. Split-system gas furnace with air conditioner that

meets the minimum federal guidelines for efficiency. Tankless gas water heater that meets the minimum

federal guidelines for efficiency; individual water heaters in each multifamily apartment.

Methodology and Assumptions The analyses for each of the prototypical building types begins with a design that meets the minimum 2016 prescriptive requirements (0% compliance margin). The energy budget is established by compliance with the prescriptive measures for each climate zone.

Methodology and Assumptions

Methodology and Assumptions Using the 2016 baseline as the starting point, different energy efficiency measures are identified and modeled in each of the prototypes to determine the projected energy (Therm and kWh) and compliance impacts. Performance runs were conducted to develop packages: 15% (CALGreen Tier 1) 30% (CALGreen Tier 2)

Methodology and Assumptions Evaluation showed that both single family and multifamily prototypes are feasible in most climate zones. In climates where it was not feasible, targets were relaxed to an appropriate level.

Methodology and Assumptions

Methodology and Assumptions Efficiency Packages

Three efficiency packages for each climate zone: The federal government does not allow government agencies to require the use equipment that exceeds the minimum standard requirement. Includes at least one package for each climate zone that does not require installing equipment with higher efficiencies than federally mandated.

Methodology and Assumptions Efficiency Packages In climates where the PV Compliance Credit (PVCC) is available PVCC in addition to efficiency measures was evaluated to achieve Tier 2. 1) Envelope: focuses on building envelope

measures and includes efficient hot water pipe distribution and cooling fan efficiency measures.

2) Equipment: Use of HVAC and water heating equipment that are more efficient than federal standards combined with efficient envelope measures.

3) PV Credit: Utilize the PV compliance credit (PVCC) available in all climate zones except

Methodology and Assumptions PV Performance Packages PV-Plus Tier 2 efficiency package (where cost effective) Install a PV system sized to offset approximately 80%

of the total household energy use based on TDV energy.

PV sizing is consistent with the methodology included in the California Energy Commission’s proposed Solar PV Ordinance being developed by the CEC.

Prescriptive PV sizing is based on Climate Zone and home size.

Methodology and Assumptions Prescriptive PV Sizing

Methodology and Assumptions PV Performance Packages TDV-Zero Tier 2 efficiency package Install a PV system sized to offset 100% of

building energy use based on TDV energy, including appliances and plug loads.

This is consistent with the requirements of the CALGreen Zero Net Energy Design tier.

Methodology and Assumptions Cost Effectiveness The standard residential rate was applied. The applicable residential time-of-use (TOU) retail rate was applied to all cases with PV systems. Any annual electricity production in excess of annual electricity consumption is credited to the utility account at the applicable wholesale rate.

Methodology and Assumptions Cost Effectiveness The benefit-to-cost ratio is a metric which represents the cost effectiveness of energy efficiency over a 30-year lifetime. A value of one (1) indicates the savings over the life of the measure are equivalent to the incremental cost of that measure. A value greater than one represents a positive return on investment. Lifecycle Customer Benefit-Cost Ratio = (Annual utility cost savings * Lifecycle cost factor) / (First incremental cost * Financing factor)

Methodology and Assumptions Cost Effectiveness The lifecycle cost factor includes the following assumptions: 30-year measure life & utility cost savings No utility rate escalation (conservative

assumption)

Methodology and Assumptions Cost Effectiveness The financing factor includes the following assumptions: 30-year financing term 4.5% loan interest rate 20% average tax rate (to account for tax savings

due to loan interest deductions) Simple payback is calculated using the equation below. Simple payback = First incremental cost / Annual customer utility cost savings

Methodology and Assumptions Greenhouse Gas Emissions Equivalent CO2 emission savings were calculated using the following emission factors. Electricity factors are specific to California electricity production.

Results Cost effective analysis including evaluating

three efficiency packages and two PV performance packages was completed for all sixteen climate zones.

Evaluations looked to identify cost effective Tier 1 and Tier 2 packages for both single family and multifamily prototypes at the CALGreen performance targets of 15% and 30%.

When initial proposed packages were found to not be cost effective, multiple computer runs were conducted to identify a cost effective package.

Results If Tier compliance was not feasible targets

were relaxed to achieve cost effectiveness. In other climates no cost effective package

could be identified. In almost every climate there was no cost

effective way to achieve Tier 2 efficiency levels without the PV compliance credit.

All Tier 2 packages include PV.

Results Proven cost-effective measures with wide market acceptance in typical residential construction were selected for greater application. Achieving greater performance is feasible using advanced design strategies and measures.

Results Typical cost effective measures included: QII Reduced infiltration window & door performance High efficiency HVAC equipment High performance attics and walls Cool roofs HERS verification of measures PV credit Hot Water pipe insulation and compact

distribution

Quality Insulation Installation (QII)

HERS rater verification of insulation quality according to the procedures outlined in the 2016 Reference Appendices RA3.5 QII is a pre-requisite for all the voluntary tiers in 2016 CALGreen.

What is QII & Why is it Important?

QII inspection is performed by a certified HERS rater and ensures that: The envelope is

insulated and air sealed properly

Applies to both insulation and air sealing

Studies show that without QII, insulation quality does not meet manufacturer guidelines


Batts shall be correctly sized to fit snugly at the sides and ends, but not be so large as to buckle. Batts shall be cut to fit properly without gaps. Insulation shall not be doubled-over or compressed.


Rim joist shall be insulated.

Quality Insulation Installation (QII) Batts shall be cut to butt-fit around wiring and plumbing, or be split (delaminated) so that one layer can fit behind the wiring or plumbing, and one layer fit in front.


Installation shall uniformly fill the cavity side-to-side, top-to-bottom, and front-to-back.

Quality Insulation Installation (QII) Where necessary, batts shall be cut to fit properly - there shall be no gaps, nor shall the insulation be doubled-over or compressed.

Current Practices and Trends QII is well established, but not widespread or consistent CalCERTS registry data: 24% single family homes 13% multifamily buildings

Required by some local ordinances QII presents challenges for: Installer Building Inspector HERS Rater

Reduced Infiltration (ACH50): HERS rater field verification and diagnostic testing of building air leakage according to the procedures outlined in the 2016 Reference Appendices. The default infiltration assumption for single family homes is 5 air changes per hour at 50 Pascals (ACH50)4 and the reduced level applied in this analysis is 3 ACH50.

Reduced Infiltration (ACH50):

Reduced Infiltration (ACH50): All gaps in the air barrier greater then 1/8 inch shall be caulked, or sealed with expansive or minimally expansive foam.

Reduced Infiltration (ACH50): Requires HERS Rater to perform field verification and diagnostic testing of newly constructed homes for air infiltration to verify compliance

Window Performance Reduce window U-value from the prescriptive value of 0.32 to 0.30 in all climates and reduce the solar heat gain coefficient (SHGC) from the prescriptive value of 0.25 to 0.23 in climate zone 2, 4, 6 through 16. In climate zones 1, 3, and 5 there is no prescriptive SHGC requirement and the default value of 0.50 was used.

Window Performance

Window Performance Significant credit is

granted because windows affect both the heating and cooling loads.

Windows can contribute up to 50% of heat accumulating indoors.

In most climates it is the largest source of heat gain

Door Performance Install insulated doors that meet a U-value of 0.20 at

the front entry and doors between the house and garage.

The code default is a U-value of .50 If the door has more than 50% glazing then it is

modeled as a window

Cool Roof Install a roofing product that’s rated by the Cool Roof Rating Council to have an aged solar reflectance of 0.20.

Cool Roof This measure only applies to climates zones where this is not already required prescriptively. Prescriptive requirement is 0.20 in climates zones 10-15. No requirements for climates zones 1 – 9 and 16.

Exterior Wall Insulation: Increase wall cavity insulation from R-19 to R-21 in 2x6 walls.

High Performance Attics (HPA) For climates where HPA is not already prescriptive under the 2016 code (CZ 1-3, 5-7), increase attic ceiling insulation to R-38 and add insulation under the roof deck between framing (R-13 for roof with air space, R-18 for roof without air space).

High Performance Attic Insulation at roof deck OR ducts in conditioned space to reduce loads and increase duct system efficiency Standard vented attic Conventional ceiling and duct insulation Duct leakage 5% Alternative: Unvented /sealed attic

High Efficiency Furnace Upgrade furnace to a condensing unit with an efficiency of 92% AFUE. Federal requirement is 80% minimum efficiency.

High Efficiency Air Conditioner Upgrade air conditioner efficiency beyond federal efficiency minimum to either SEER 15 / EER 12.5 or SEER 16 / EER 13 2016 minimum efficiency: SEER 14 / EER 11.2

High Efficacy Fan Upgrade the fan in the furnace or air handler using an electronically commutated motor (ECM) that meets an efficacy of 0.3 Watts/cfm or lower operating at full speed. Code requirement is 0.58 Watts/cfm.

High Efficacy Fan Fan watt draw is verified by a HERS rater according to the procedures outlined in the 2016 Reference Appendices.

High Efficacy Fan New federal regulations that go into effect July 3, 2019 are expected to result in equivalent performance for all newly manufactured furnaces.

Refrigerant Charge Verification: HERS rater verification of proper air conditioner refrigerant charge according to the procedures outlined in the 2016 Reference Appendices.

Refrigerant Charge Verification: This measure only applies to climates zones where this is not already required prescriptively. Not required in climate zones 1, 3-7 and 16.

R-8 Duct Insulation Increase duct insulation to R-8. This measure only applies to climates zones where R-8 ducts are not already required prescriptively. R-8 duct insulation not required in climate zones 3, and 5-7.

High Efficiency Water Heater Upgrade tankless water heater to a condensing unit with a rated Energy Factor (EF) of either 0.94 or 0.96.

Hot Water Pipe Insulation: As of January 1, 2017 the 2016 California Plumbing Code requires pipe insulation levels that are close to that required if taking the Title-24, Part 6 pipe insulation credit.

Hot Water Pipe Insulation: This credit will be obsolete under the 2016 energy code, however, the HERS-Verified Pipe Insulation Credit, as defined in the 2016 Reference Appendices will remain.

Hot Water Compact Distribution:

HERS rater verification of compact distribution system requirements according to the procedures outlined in the 2016 Reference Appendices. This measure was applied to multifamily buildings only. Many multifamily buildings with individual water heaters are expected to easily meet this credit with little or no alteration to plumbing design.


This measure also requires verification of pipe insulation per the HERS-Verified Pipe Insulation Credit. Assumption is 60 linear feet per dwelling unit of 1/2in insulated pipe.

PV Compliance Credit: To be eligible for this compliance credit a PV system must comply with minimum capacity: 2 kW DC per single family

home with no more than 2,000 ft2 of conditioned floor area

1 kW DC per multifamily unit with no more than 1,000 ft2 of conditioned floor area is required

2,430 ft2 prototype the minimum capacity as calculated by CBECC-Res is

PV Compliance Credit: The credit was developed to give builders an option with which to trade-off High Performance Attics and Walls, and to begin preparing for ZNE requirements. In the 2019 Standards the PV trade-off goes away.

Single Family Cost Effectiveness Analysis

A comparison of cost effectiveness for each climate zone and five cases is presented in Figure 1.

Single Family Cost Effectiveness Analysis

Cost effectiveness results were divided into the different strategies (Envelope, Equipment, and PV Credit) as well as for the two PV performance packages (PV-Plus and TDV-Zero). Envelope HPA, HPW, efficient hot water pipe distribution and

cooling fan efficiency measures. Efficiency High efficiency equipment water heating equipment,

efficient envelope measures if necessary PV Credit PV Plus TDV Zero

Tier 1 , Tier 2 & PV Credit Packages

Tier 1 , Tier 2 & PV Credit Packages

Using high efficiency equipment is shown to result in the highest return on investment in many climates. Cost effective packages that do not require equipment with efficiencies better than federally mandated values were developed to avoid federal preemption prohibitions.

Tier 1 , Tier 2 & PV Credit Packages Tier 1 Envelope packages were found to be cost

effective in climate zones 1 through 5 and 9 through 16.

The Tier 1 threshold in climate zone 4 was reduced to 10% to meet the cost effectiveness criteria.

No cost effective Tier 1 Efficiency packages were identified in climate zones 6 through 8.

PV Packages The PV system

capacity for the PV-Plus packages is sized to provide approximately 80% of estimated annual kWh consumption.

The required TDV-Zero PV capacity ranges from 3.1 kW DC in the mild climates (CZ5 and 7) to 7.7 kW DC in hot climates (CZ15).

PV Packages Adding PV beyond the amount needed to offset

electricity use reduces cost effectiveness in all cases.

The Zero-TDV cases are cost effective in only four climate zones and benefit-cost ratios are consistently lower in all climates.

The customer is paid for excess electricity generation beyond what is consumed by the dwelling but only at the wholesale rate which is

substantially lower than the retail rate.

Tier 1 Packages: CALGreen defines Tier 1 as showing a 15% or

greater Title 24 compliance margin compared to the Standard Design.

The intent of the Efficiency tier in this study was to find cost effective packages that meet the CALGreen Tier 1 criteria without mandating the installation of PV or high efficiency equipment that exceed federal minimum levels.

The recommended approach should be to encourage adoption of efficiency measures rather than utilize the PVCC to meet the Tier 1 compliance requirements.

Tier 1 Packages: Based on the lifecycle benefit-to-cost ratio,

there are exist multiple cost effective packages to meet Tier 1 for single family and low-rise multifamily homes.

There are several climates where the compliance margin targets are lowered to maintain the cost effectiveness criteria and other climates where no cost effective efficiency packages were identified.

PV-Plus Packages: CALGreen defines both Tier 2 and ZNE Tier performance levels. The ZNE Tier requires that the building includes a PV system sized to offset 100% of the TDV energy of the building (achieve an Energy Design Rating of 0). Dwellings with gas and electricity, that met the ZNE Tier criteria were: Generally not cost effective or Marginally cost effective.

PV-Plus Packages: A PV-Plus package was developed that limited the size of the PV system to no larger than 80% of the annual estimated electricity use of the building and combine it with efficiency measures that are cost effective in all climate zones.

Multifamily Results It is generally more challenging to achieve

equivalent savings targets for the multifamily cases than for the single family cases.

Reduced exterior surface area per floor area diminishes the impact of envelope measures.

The PV credit is also much smaller because it is offsetting only high performance walls

High performance attic is not applied to the multifamily prescriptive design because ducts are already assumed to be within conditioned space.

Multifamily Cost Effectiveness Analysis All multifamily results are presented on a per dwelling unit basis. Cost effectiveness results are presented for all of the three efficiency packages described previously Envelope Equipment PV compliance credit

Two PV performance packages PV-Plus and TDV-Zero

Multifamily Cost Effectiveness Analysis

Multifamily Package Recommendations

Based on the multifamily cost effective analysis, two reach code packages were developed. Tier 1 Efficiency only: Where cost effective packages were identified, the

15% compliance margin target (CALGreen Tier 1) were used.

A cost effective 15% package was not identified for climate zone 10, so a 10% compliance margin target was used

No cost effective efficiency only packages were identified for climate zones 3 through 9

Multifamily Package Recommendations PV-Plus: Cost effective packages with efficiency and PV were identified in all 16 climate zones, but the compliance margin targets in all climates were lowered below 30% in all cases to be cost effective. It is assumed that the PV compliance credit can be used to meet these targets (except in climate zones 6 and 7). It is also assumed that a PV system is installed per the methodology developed for the proposed Solar PV ordinance.

Alterations and Renewables Considerations When is the PV

system generating energy?

When is the building using the energy?

Time of use rates Electric appliances PV sizing to offset

gas use Battery storage

Case Studies ZNE Homes Achieving ZNE requires a combination of energy efficiency and renewable energy production. Reduce the amount of energy a home uses. Efficient envelope design strategies Day lighting, as appropriate Energy-efficient technologies including lighting, HVAC

and water heating Optimize the way the building actually operates Plug loads System controls

Install renewable generation on-site to meet the remaining energy needs of the building. Installed renewable resources have been primarily photovoltaic (PV) panels.

Case Studies ZNE Homes

Case Study: Habitat for Humanity San Joaquin, Dream Creek Subdivision Prescriptive Versus Performance in Practice The case study residence was designed to

exceed the 2008 Title 24 Energy Standards in effect when it originally went for permit.

It still complies with the 2016 Title 24 Energy Standards.

The home is in the Habitat for Humanity San Joaquin, Dream Creek subdivision in Stockton, California, and it is a PG&E ZNE (zero net energy) production builder demonstration project.

Case Study: Habitat for Humanity San Joaquin, Dream Creek Subdivision

A goal of the project was to show that it is possible to achieve ZNE goals cost-effectively. Efficient architectural design Advanced framing and high performance enclosure High performance heating, ventilation, and air conditioning

(HVAC) Water heating Water conservation Lighting Renewable energy (PV)

Case Study: Habitat for Humanity San Joaquin, Dream Creek Subdivision

Case Study: Habitat for Humanity San Joaquin, Dream Creek Subdivision Space heating, cooling and ventilation system: Ducted mini split heat pump with 10.3 HSPF, 15.1

SEER and 11.2 EER, HERS-verified minimum airflow, SEER and fan efficacy watts/cfm1

R-8 ducts entirely located in conditioned space and sealed and tested for leakage, HERS-verified reduced duct leakage and duct location

HERS-verified indoor air quality (IAQ) mechanical ventilation1

Case Study: Habitat for Humanity San Joaquin, Dream Creek Subdivision Water heating system: Tankless gas water heater with 150,000 Btuh

input and 0.82 energy factor, located near the center of the house so that the longest hot water pipe run is 12', HERS verified compact distribution system

Solar photovoltaic (PV) system: 2.8 kW PV system installed

Case Study, Davis City Hall City Hall-wood framed w/masonry cladding Council Chambers-wood framed Planning trailer-wood framed

City Hall–1927 Chambers–1974 Planning Trailer-1990 City Hall–17,348 Chambers–4,217 Planning Trailer–1,440 Office: 18,788 (City Hall and Planning) Assembly: 4,217 (Council Chambers) Goal - Zero Net Carbon for the historic City Hall building

Case Study, Davis City Hall Energy efficiency improvements in 2011 Perform the audit on City Hall Air seal the building envelope to address the

infiltration Insulate the crawl space and attic to improve the

efficiency of the building envelope Redesign and rezone the HVAC system to address

past changes in the floor plan Install new ductwork based on the redesign and

rezoning of the building

Case Study, Davis City Hall Proposed energy efficiency improvements 2017/18 to get to ZNE and Zero Net Carbon at City Hall. Replacing the original single pane wood framed

windows with double pane wood framed windows having a U-factor of .31 and SHGC of .22.

Replacing T-12 and T-8 luminaires with LED luminaires. Lighting controls

Replace the existing HVAC package units with VRF heat pump units (switch fuel to achieve zero carbon emissions).

Install a Building Management System. Install 60 kW PV system. Remaining energy offset with offsite PV

Proposed CEC Changes 2019 Quality Insulation Installation (QII) Change QII from compliance option to prescriptive requirement. Single family and multifamily Applies to new construction and additions over

700 sq. ft.

Still not mandatory can be traded off with efficiency measures.

Proposed CEC Changes 2019 High Performance Walls .043 U-factor in climate zones 1, 11-16. 2 x 6 @16” O.C. R 7.5 continuous insulation

PV trade-off for HPA and HPW is going away in 2019

Proposed CEC Changes 2019 High Performance Attic (HPA) Prescriptive measure where cost effective. From R-13 to R-19 underdeck batt for roof with air

space (tile roof). Applies to additions > 700 sq. ft.

Proposed CEC Changes 2019 Windows and Doors U-factor from .32 to .30 SHGC from .25 to .23 in climate zones 2, 4 and

6-15. No SHGC for climate zones 1, 3 5 and 16. Leakage from .3 to .2 cfm per sq. ft.

In 2016 doors > 50% glazing were considered windows. In 2019 doors > 25% glazing are considered windows. Non glazed doors U-factor < 0.20 was 0.50 (NFRC Rating)

Proposed CEC Changes 2019

Proposed CEC Changes 2019 Zero Net Electricity Battery Storage Credit Hot Water Storage Credit Rebates for Solar not available for code

required PV

Proposed Legislation SB 71- Statutory PV Requirement SB 1414- Plan to Improve HVAC and

water heater code compliance Bill to require rigid duct in residential

construction. Bill to require prevailing wage for

residential construction workers

Questions?

Greg Mahoney [email protected]

zero net energy: getting there through code · 2017. 8. 1. · zero net energy: getting there...

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