California Multi-Family New Homes

A Third-Party Program of the Pacific Gas and Electric Company (PG&E)

Design for Net Zero: Multi-Family Modeling

and Measuring Techniques

July 19, 2011

October 2009 

Sponsored by PG&E

“PG&E” refers to Pacific Gas and Electric Company, a subsidiary of PG&E Corporation.© 2010 Pacific Gas and Electric Company. All rights reserved.

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Program DescriptionPublic service programCash Incentives Energy Design AssistanceProject RoundtableEducational Opportunities Program Coordination

Facilitate energy efficient design and construction in new multi-family

housing through cash incentives and design assistance

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Eligible CustomersMulti-family buildings in PG&E

service territory: 3 or more attached units New construction Exceed 2008 Title 24 Standards

by at least 15% Submit complete application

package prior to construction start

Complete construction and verification by December 31, 2015

* Please contact HMG if you are unsure of the eligibility of your project.

Program Process Participant provides HMG with:

Completed application Title 24 documentation Architectural plan-set (+MEP) Service territory verification W9 Form

HMG conducts a plan review to verify energy measures, estimated savings, % better than Title 24

Project enrolled, receives ‘Letter of Enrollment’ Third party HERS verification conducted during construction to

ensure energy measures installed* HMG verifies any changes to project since enrollment and ensures

as-built still exceeds Title 24 by at least 15% Project completed and incentives paid

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*Note: the program verification protocols are in addition to any HERS measures on your Title 24

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Incentive Information

Developer Incentives: $100 per unit plus incremental incentives based on energy savings HERS verification incentive: $60 per unit (max of $12,000 per project)

Energy Consultant Incentives: $50 per unit (max of $10,000 per project)

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Program Contact Information

Toll Free: 866-352-7457 Email: cmfnh@h-m-g.com Website: www.h-m-g.com/multifamily

Program Manager: Amy Barr, barr@h-m-g.comPlan Review Manager: Linda S. Murphy, murphy@h-m-g.comAssociate Manager: Sophia Hartkopf, hartkopf@h-m-g.comAssociate Plan Review Manager: Keith Sage, sage@h-m-g.comProgram Associate: Ashley Heath, heath@h-m-g.comProgram Assistant: Lauren Moreno, moreno@h-m-g.com

Design for Net Zero: Multi-Family Modeling and Measuring

Techniques

Definition of Zero Net Energy

The California Energy Efficiency Strategic Plan

The plan adopts three “zero net energy” strategies: All new residential construction in

California will be zero net energy by 2020

All new commercial construction in California will be zero net energy by 2030

Fifty percent of existing buildings will be zero net energy by 2030

Definition of Zero Net Energy

Zero net energy generally means a building will consume no net energy in a typical year. Amount of energy demanded by the building is

equal to the amount provided by on‐site or near‐by renewable energy sources. When the building is producing more electricity

than it needs, it exports its surplus to the grid. When the building requires more electricity than is

being produced on‐site, it draws from the grid.

Definition of Zero Net Energy

ZNE Loading Order Energy efficiency is the highest priority. Generally, when constructing a ZNE building, energy

efficiency measures can result in up to 70% savings relative to existing building practices.

Allows for renewables to meet the remaining load.

ZNE is not a ‘electric-only’ concept Need to account for all fuel uses Need to account for all end-uses

Heating, cooling, ventilation, DHW, lighting, plug loads, appliances

Steps to Net Zero

Site selection Load reduction Envelope and massing Infiltration reduction Lighting Appliances Misc. plug loads

HVAC and DHW systems efficiency Renewable energy Commissioning Occupant Behavior

Integrated Design Process

Engage all design team members early in design

Building Analysis Tools

Whole building energy modeling Natural ventilation Computational Fluid Dynamics (CFD)

Thermal comfort ASHRAE 55 Toolkit, EnergyPlus, California Simulation

Engine for compliance with 2013 Title 24 Standards, Renewable energy systems

Microsoft Excel

Whole Building Energy Modeling

Comparative analysis to determine relative impacts of design and energy efficiency measures

Annual analysis to estimate the annual energy consumption of building

Code compliance

Green building rating programs

Estimating w/ Energy Modeling

Many energy modeling tools at our disposal with specific capabilities and setbacks compared to the others Capability to model complex measures Capability to model emerging technologies Capability to perform code compliance Capability to perform weather normalization Difficulty to use software, learning curve Lack of robust HVAC system types Inability to model multiple HVAC system types Inability to accurately model baseloads

Estimating w/ Energy Modeling

EnergyPro / Micropas: lack of advanced controls, uses fixed assumptions for lighting and appliances per T24 Primarily for code compliance Limited systems options

eQuest More system choices Can input detailed lighting and plugs

TREAT Targeted toward retrofits, can be used for NC Weather/billing data normalization (bill matching)

EnergyPlus very detailed with max flexibility and capability very steep learning curve

Measuring Actual Performance

Continuous calibration of energy model

Facilitates improved understanding of which design features performance is as expected, better, or worse

Practical implications for future projects

Commissioning of building will improve likelihood systems operating as intended

Site Selection

Affects ability to utilize conditions for Natural Ventilation Passive solar design features Solar PV Solar DHW

Optimize for all four with new developments

More limited with urban infill and redevelopment projects

Envelope and Massing

Thermal mass and passive solar design

Insulation Windows Overhangs Wall and roof construction Advanced wall framing

Quality Insulation Installation (QII)

Use Overhangs

Shading opportunities

Thermal and Pressure Boundaries

Thermal boundary around a building is the line that stops heat from moving between unconditioned to conditioned

Pressure boundary is the line that stops air movement between unconditioned to conditioned

These two boundaries need to be aligned Effective insulation u-value reduced if not

Infiltration Airflow Driving Forces

Wind Effects Positive pressure on windward side, negative pressure on

downwind side Mechanical Effects Induced by exhaust fans and ventilation fans

Stack Effect Negative pressure at the foundation brings air into

structure, heats and rises, and pressurizes the top of building and exfiltrates

Stack Effect Reduction

Compartmentalization Isolation of units from each other and corridors, shafts,

elevators, and stairwells Instead of sealing the exterior of the building only

Local exhaust fans Instead of central exhaust fans

Modeling Envelope Tightness

Inputs Specific leakage area

3.8 ducted HVAC / 3.2 non-ducted HVAC is default per CEC

Envelope & HVAC Interaction

High performance envelope system can result in smaller HVAC equipment

Tightly sealed envelope and residential mechanical ventilation per Title 24-2008

Lighting, Appliances, and Misc. Plug Loads

Large component of total MF building energy use Hardwired high-efficacy lighting to limit use of

incandescent lamps

Lighting Controls Occupancy sensors Vacancy sensors

Energy Star appliances Plug load sensors

Lighting, Appliances, and Misc. Plug Loads

The key is what is the lighting baseline? How low wattage and light output can you go without

affecting lighting quality Poor lighting levels or poorly designed layout may result in

tenants installing incandescent portable lamps CEC approved software (EnergyPro) requires default

average wattage for high efficacy lighting instead of actual wattage

Other non-CEC approved have more flexibility Need to calculate actual lighting for PV design

Heating Systems

Don’t oversize the heating system

ZNE MF buildings do not need to have exotic super engineered complex HVAC systems

Use high-efficiency equipment Furnaces w/modulating capabilities Condensing furnaces Heat pumps (air-to-air, water-source, ground-source) Hydronic systems

Heating Systems

Distribution systems Duct sizing (fan power) tight ducts (heat loss)

Utilize all available HERS measures

Cooling Systems

If cooling is installed, don’t over-size the cooling system Oversizing causes excessive cycling of the compressor

which wears down the equipment Will operate inefficiently at part load

High-efficiency DX equipment Standard equipment (heat pump, a/c) VRF: EnergyPro submitted new algortithims to model

these system more accurately in DOE2 (high-rise only) Mini-split

Utilize all appropriate HERS measures

Mitsubishi City-Multi VRF System

Ventilation

Natural ventilation Thermal comfort analysis to ensure comfort of tenants

Passive options, z-ducts, operable window, trickle vents Requires advanced tools to model

Mechanical ventilation with heat recovery

Methods of Ventilation

Natural Local exhaust only Central exhaust “Balanced” system with central supply ventilation air to

corridor DOE-2 OA-FROM command

Central Exhaust Systems

Advantages Cheap and easy to build

Dis-advantages Difficult to balance Difficult to maintain Susceptible to fluctuations in system pressure resulting

from wind and stack effect Makes compartmentalization impossible

Domestic Hot Water Systems

High efficiency condensing DHW or boiler Instantaneous DHW Central DHW Modulating condensing boilers with custom curves EnergyPro can’t model DHW or boiler performance curve EnergyPlus and eQuest can

Solar thermal Need to combine tools

Renewable Energy Options

Rooftop to conditioned floor area ratio impacts potential Low-rise can likely

incorporate more solar with a large rooftop area

Small rooftop of typical high-rise MF will limit ability to maximize solar

Renewable Energy Options

Solar Thermal for DHW CSI calculator F-chart TRANSYS Poly-sun and T-Sol (proprietary)

Solar PV for electricity (Hourly output is necessary to know net balance) PV Watts full version CECPV F-chart TRANSYS

Software: What’s Coming Up

California simulation engine Will be basis for compliance with 2013 title 24 code Goal to more accurately estimate

Solar gain impact on cooling energy and peak load Building shell and interior mass on cooling loads and indoor

temperature variation Ventilation interaction with building mass and its impact on

cooling energy and peak load Adds new capabilities for comfort analysis, mechanical

ventilation Integrate HERS II procedures

EnergyPlus an option for commercial, high-rise residential buildings

Questions?

Jeff Staller916-962-7001

staller@h-m-g.com

Abhijeet Pande916-962-7001

pande@h-m-g.com