# Presentation: 535633

## Zero Energy Homes Opportunities for Energy Savings:

- Navigant Consulting, Inc.
- 1801 K Street, NW
- Washington D.C. 20006
- www.navigantconsulting.com

**Zero Energy Homes Opportunities for Energy Savings:**
**Defining the Technology Pathways through Optimization Analysis**

- Prepared for U.S. Department of Energy
- Building Technologies Program
- NREL Energy Analysis Seminar
- December 11, 2003

## Today’s Agenda

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

**Today’s Agenda**

- 4

- Optimization Analysis

- Systematic Approach

- 2

## Today’s Agenda    Introduction

- Introduction

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

- 4

- Optimization Analysis

- Systematic Approach

- 2

## Zero Energy Homes (ZEH) are not a new concept and have been successfully demonstrated in many applications and climates through unique, potentially costly designs.

**Introduction**    Zero Energy Homes Concept

**Zero Energy Homes (ZEH) are not a new concept and have been successfully demonstrated in many applications and climates through unique, potentially costly designs.**

**Notes:**
The ZEH homes shown are in Virginia, Florida, Arizona, California, and Michigan.

## Leading to the question: What are the affordable technology pathways to achieving ZEH in each application and climate?  

**Leading to the question: What are the affordable technology pathways to achieving ZEH in each application and climate?  **

**Introduction**    ZEH Pathways

**In order for ZEH to be widely embraced by the home building community, a variety of affordable design solutions are necessary for many applications and climates.**

## One method to identify the technology pathways is to evaluate various technologies by choosing those that can achieve zero energy performance for the least installed cost (termed optimization).

**Introduction**   Optimization Analysis

**One method to identify the technology pathways is to evaluate various technologies by choosing those that can achieve zero energy performance for the least installed cost (termed optimization).**

## Today’s Agenda    Systematic Approach

- Introduction

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

- 4

- Optimization Analysis

- Systematic Approach

- 2

## One typical approach for assessing the cost and benefits of technologies is through simulation models.

- Individual house approach
- Whole-building design
- Weather and other unknowns are simulated
- User applies an energy-saving strategy and runs the simulation
- Many times, trial and error method to find most optimal combination of energy-saving strategies

**Typical Model Methodology**

**Baseline Model**

**Strategy 1**

**Yes**

**No**

**Strategy 2**

**Yes**

**No**

**Strategy 2**

**Yes**

**No**

**One typical approach for assessing the cost and benefits of technologies is through simulation models.**

**Systematic Approach**    Typical Models

## This process can be time-consuming and the results could be less than optimal.

**This process can be time-consuming and the results could be less than optimal.**

**Systematic Approach**    Typical Process

**To identify the technologies that can achieve a desired performance at a reasonable cost, the user must apply them one at a time to the baseline.**

## From an R&D planning standpoint, technology pathways for achieving a desired performance can be assessed accurately and more efficiently through an optimization model. 

- Individual house approach
- All energy end uses are evaluated simultaneously
- User has flexibility to change energy-saving strategies
- Potentially easier to model research and development technologies
- Uses linear programming to solve for the optimal combination of strategies

**Optimization Model Methodology**

**Baseline Model**

**Strategy 1**

**Yes**

**No**

**Strategy 2**

**Yes**

**No**

**Strategy 2**

**Yes**

**No**

**Systematic Approach**    Optimization Model

**From an R&D planning standpoint, technology pathways for achieving a desired performance can be assessed accurately and more efficiently through an optimization model. **

## The optimization methodology was first applied to single-family detached homes, where a systematic approach was taken to model technologies and their interactions.

**Systematic Approach**    Whole House Design

**The optimization methodology was first applied to single-family detached homes, where a systematic approach was taken to model technologies and their interactions.**

## To encompass aspects of a newly constructed home, the model was designed to account for envelope, equipment, and solar components.

**Systematic Approach**    Whole House Components

**To encompass aspects of a newly constructed home, the model was designed to account for envelope, equipment, and solar components.**

**Solar**

**Equipment**

**Envelope**

## The user simply enters the desired total energy use and the model returns the optimal portfolio of building technologies for saving energy and cost.

**Constraint**

**  **
**Target Total Energy Use**

**Systematic Approach**    Optimization Process

**The user simply enters the desired total energy use and the model returns the optimal portfolio of building technologies for saving energy and cost.**

## The model evaluates various components simultaneously using linear programming to choose the optimal system of technologies.

**Systematic Approach**    Optimal System

**The model evaluates various components simultaneously using linear programming to choose the optimal system of technologies.**

**Cost**

**Energy Use**

**Target**

**Minimize Cost**

**Optimal Portfolio**

## Today’s Agenda    Model Description

- Introduction

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

- 4

- Optimization Analysis

- Systematic Approach

- 2

## Technology

**The model was created through three steps to characterize the prototypes, technologies, and interactions.**

**Technology**
**Characteristics**

**Building Loads**

**Outputs**

**Technology **
**Interactions**

**Analysis **
**spreadsheets**

- Includes
- 16 cities
- Heating/Cooling Loads
- From *Residential Heating and Cooling Loads Component Analysis* J. Huang et al, LBNL 1998

**EIA Data, Building America, DOE Appliance Standards**

**Envelope Load Contribution Factors**

** ****Optimized Portfolio of Technology Options**

- Includes
- Lowest First Cost for Target Consumption
- Can be optimized for other constraints (I.e. LCC, etc...)

**Data Inputs/Assumptions **
**Spreadsheet**

- Includes
- Interaction Equations
- Optimization Algorithms

- Includes
- Cost
- Typical Size
- Efficiency
- Annual Consumption Estimates

## Previous studies using building models have already examined the various component building loads, which were utilized in the model.

**Model Description**    Building Loads

**By Region (City)**
- New England
- Mid-Atlantic
- East North Central
- West North Central
- South Atlantic
- West South Central
- Mountain
- Pacific North
- Pacific South

**By Type**
- Single-Family Detached
- Single-Family Attached
- Mobile
- Multi-Family

**By Vintage**
- Pre-1950s
- 1950-1979
- 1980-1989
- Post 1989

*Source: **Residential Heating and Cooling Loads Component Analysis** J. Huang et al, LBNL 1998*

## Next, the technologies were added to the model and each with three possible cases: baseline, best available, and maximum technology.

**Best Available**
- Highest Efficiency on the Market

**Maximum**
- Highest Efficiency Possible

**Model Description**    Technology Characteristics

**Next, the technologies were added to the model and each with three possible cases: baseline, best available, and maximum technology.**

**Equipment Efficiency Constraints and Installed Costs**

* **Source: Residential Optimization Model Version 5.4, NCI*

| Technology  | Equipment | Value | Units | Baseline | Best Available | Maximum |
| --- | --- | --- | --- | --- | --- | --- |
| Heating | Gas Furnace | Efficiency | AFUE | 80 | 96 | 150 |
|   |   | Installed Cost | $ | 1300 | 1800 | 5398 |
| Cooling | Central A/C | Efficiency | SEER | 10 | 18.6 | 20 |
|   |   | Installed Cost | $ | 2080 | 3500 | 3809 |
| Heat Pump | Electric Heat Pump | Efficiency | HSPF | 6.8 | 9.8 | 10 |
|   |  | Installed Cost | $ | 2930 | 5600 | 5847 |

**Baseline**
- Typical Installed Efficiency

**Notes:**
Once the envelope prototypes and inputs were complete, comprehensive sets of equipment technologies were inserted into the model.  For each technology, such as heating equipment, we have modeled three possible cases: baseline, best available, and maximum technology.  The baseline case represents the typically installed efficiency, best available represents the current highest efficiency on the market, and maximum technology represents the highest efficiency possible with future advancements. 

## Finally, the technology interactions were built into the spreadsheet.

**Finally, the technology interactions were built into the spreadsheet.**

## ILLUSTRATIVE

**Detached Single-Family House **
**In Atlanta**

**ILLUSTRATIVE**

**As an example, I would like to walk through the potential steps in our optimization analysis.**

## ILLUSTRATIVE

**90 MBtus**

**Constraint**

**  **
**Target Total Energy Use**

**The user begins by entering in the Target Total Energy Use, which for the Atlanta prototype is 90 MBtus.**

## ILLUSTRATIVE

**Optimal Portfolio of **
**Building Technologies**

**Inputs**

**Output**

**Model Description**    Running Model

**Next, the user runs the model to get the lowest-cost portfolio of building technologies for achieving a Total Target Energy Use of 90 MBtus.**

## ILLUSTRATIVE

- Building Envelope

- Appliances

- Heating

- Cooling

- Water
- Heating

- Lighting

- Refrigerator

- Washer

- Dishwasher

- Walls

- Roofs

- Windows

- Foundation

- Insulation

- Electric Heat Pump

- Electric Heat Pump

- Gas

- Incandescent

- Electric

- Electric

- Electric

- 2X4 Wood

- 2X10 Wood

- Aluminum

- Slab

- 2X4 Wood

- 7.0

- 14

- 0.60

- 60 W

- 361

- 0.9

- .031

- Siding

- R-30

- 2 panes

- R-5

- R-15

**ILLUSTRATIVE**

**Model Description**    Portfolio Results

**Finally, the user applies the selected portfolio to transform their Atlanta home  into a house that meets both their performance and affordability goals.**

## Today’s Agenda    Model Description

- Introduction

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

- 4

- Optimization Analysis

- Systematic Approach

- 2

## The evaluation of best available technologies revealed that the technology pathways for achieving 40 and 50 percent energy savings already exist and are available on the market today for all the climate regions.

**The evaluation of best available technologies revealed that the technology pathways for achieving 40 and 50 percent energy savings already exist and are available on the market today for all the climate regions.**

**National Percentage Energy Savings**

**Notes:**
One of the major questions to be answered in our analysis was whether or not varying levels of energy efficiency are possible for each of the climate regions, and to what extent are those technologies available in the market today.  The evaluation of best available technologies revealed that the technology pathways for achieving the 40 and 50 percent energy reduction targets already exist and are available on the market today for all the climate regions.  The chart illustrates that installing the highest efficiency technologies currently available in new homes reduces energy requirements by 57 percent on average across all the climate regions, well above the 50 percent target. 

## In the maximum technology scenario, installing emerging technology pathways in new homes reduced energy requirements by 69 percent on average for all climate regions.

**In the maximum technology scenario, installing emerging technology pathways in new homes reduced energy requirements by 69 percent on average for all climate regions.**

**Optimization Analysis**    70 Percent Energy Savings

**National Percentage Energy Savings**

**Notes:**
When examining the maximum technology scenario, the overall energy savings approached 70%. Identified and emerging technologies installed in new homes reduce energy requirements by 69 percent on average for all climate regions.  To reach 70 percent energy reduction nationwide, new technologies will have to be developed to supplement the currently identified emerging technologies.  There may also be other technologies, or more importantly, combination of technologies and systems not evaluated which may also achieve some additional savings not evaluated in this analysis.  That said, achieving savings approaching 70% whole house energy consumption will be difficult.

## Though many of the technologies exist or are currently being developed to reach 70 percent energy savings, they are too expensive to be accepted into the market and achieve the desired level of energy performance.

**Though many of the technologies exist or are currently being developed to reach 70 percent energy savings, they are too expensive to be accepted into the market and achieve the desired level of energy performance.**

**Optimization Analysis**    40 to 70 Percent Energy Savings Cost

**Additional Installed Cost of Energy Saving Technologies**

**Therefore, research and development for lower cost, more efficient technologies is needed to reach the ZEH future.**

**Notes:**
Identifying the technical solutions is the first step towards ZEH.  The next is to identify whether or not the technologies available, or being developed, are attractive to the market.  While there are many market attributes to satisfy, we focused on initial cost as a primary driver to market acceptance.  Many of the technology pathways exist or are currently being developed to ensure that solutions to achieve zero energy performance will be available to the majority of residential building applications, but they must be affordable in order to gain greater acceptance and widespread application.  At current installation costs, the technology pathways are too expensive to achieve the desired levels of energy performance.

The chart illustrates that reducing energy consumption by 40 percent in new homes adds $1,100 on average to the typical installed cost. Another 10 percent reduction in energy consumption, adds $3,200 to the typical installed cost. 

Installing maximum energy conservation technologies in new homes adds $12,800 to the typical installed cost of new homes, while achieving approximately 70 percent energy reduction.  Cost reduction research and development will be necessary, in addition to developing new technology pathways for reaching the 70 percent energy reduction target, to cut costs of existing and emerging technologies by 40 percent to meet necessary cost targets.

##   31%

** ****69%**

**  ****31%**

- Increased Equipment
- Efficiency

-  Example: Solar Thermal : 4.8 SEF
- PV: 3.5 kW

- Baseline

**Energy efficiency through better equipment and buildings can only provide 69% energy savings, while renewable energy supplies are needed for the remaining 31% to reach the zero energy level.**

**Optimization Analysis** Technology Mix

## Today’s Agenda    Technology Pathways

- Introduction

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

- 4

- Optimization Analysis

- Systematic Approach

- 2

## Since initial cost is a primary driver to market acceptance, the portfolio of technologies that could achieve zero energy performance for the least potential installed cost premium was selected for each climate.

**Technology Pathways**    Portfolios

| Technology | Severe Cold | Cold | Mixed | Hot-Humid | Hot-Dry |
| --- | --- | --- | --- | --- | --- |
| Photovoltaic | 4.81 kW | 4.67 kW | 3.87 kW | 2.30 kW | 1.88 kW |
| Solar Thermal Space/Water Heating | 42% load reduction | 44% load reduction | 65% load reduction | 100% load reduction | 100% load reduction |
| Lighting | 100 L/W | 100 L/W | 100 L/W | 100 L/W | 100 L/W |
| Water Heating | Above 2.0 SEF solar thermal | Above 2.0 SEF solar Thermal | 2.0 SEF solar Thermal | 2.0 SEF solar Thermal | 2.0 SEF solar Thermal |
| Windows | 0.10 U-Value
0.38 SHGC | 0.10 U-Value
0.18 SHGC | 0.10 U-Value
0.18 SHGC | 0.10 U-Value
0.18 SHGC | 0.10 U-Value
0.18 SHGC |
| Space Heating | Above 10.0 HSPF, 140 AFUE | Above 10.0 HSPF, 140 AFUE | 9.9 HSPF, 123 AFUE | 7.2 HSPF,
89 AFUE | 6.8 HSPF,
80 AFUE |
| Appliances | 50% reduction in small appliance loads | 50% reduction in small appliance loads | 50% reduction in small appliance loads | 50% reduction in small appliance loads | 50% reduction in small appliance loads |

**Notes:**
A portfolio of technologies that could achieve zero energy performance for the least potential installed cost premium was selected for each climate region. These technologies were then prioritized with respect to their energy savings potential across all the climate regions. 

The technologies where efficiency is maximized are highlighted in yellow.  These technologies represent the areas where significant potential energy savings remain, but existing or emerging technology is exhausted and new approaches must be developed in order to see energy savings beyond these levels.  These are also the technologies that can be further explored for additional energy savings in the climate regions that do not reach the technical target.

## From the regional portfolios, the optimal efficiency targets were identified and the technologies can be developed that will meet these needs in all the climates.

**Technology Pathways**    Optimal Efficiency Targets

| Technology | Severe Cold | Cold | Mixed | Hot-Humid | Hot-Dry |
| --- | --- | --- | --- | --- | --- |
| Appliances | 400 kWh/yr Refrigerator | 400 kWh/yr Refrigerator | 400 kWh/yr Refrigerator | 450 kWh/yr Refrigerator | 500 kWh/yr Refrigerator |
|  | 4.3 cycle/kWh Clothes Dryer | 4.3 cycle/kWh Clothes Dryer | 4.3 cycle/kWh Clothes Dryer | 4.0 cycle/kWh Clothes Dryer | 3.9 cycle/kWh Clothes Dryer |
| Walls | 0.023 u-value | 0.023 u-value | 0.033 u-value | 0.058 u-value | 0.060 u-value |
| Ducts | 5% leakage | 5% leakage | 5% leakage | 5% leakage | 5% leakage |
| Foundation | 0.033 u-value | 0.037 u-value | 0.047 u-value | 0.047 u-value | 0.064 u-value |
| Roof | 0.025 u-value | 0.025 u-value | 0.028 u-value | 0.031 u-value | 0.033 u-value |
| Space Cooling | 12.0 SEER | 12.0 SEER | 12.2 SEER | 13.3 SEER | 16.8 SEER |

**Notes:**
The priority of the technologies also determines the priority for cost reduction research and development.  Photovoltaic and solar thermal space and water heating can provide the most energy savings in all the regions, but only for a large installed cost.  It is critical that the cost of the high priority technologies be minimized to ensure that affordable solutions are available for the majority of residential building applications.

- Introduction

- 5

- 3

- 1

- 6

- Planning and Additional Analysis

- Technology Pathways

- Model Description

- 4

- Optimization Analysis

- Systematic Approach

- 2

## The optimization model was created as a planning tool and has already been used to help guide DOE’s Multi-Year Program Plan (MYPP).

**Planning** **and Additional Analysis**    Planning

## Moving to ZEH will require significant technical advances to meet performance and cost targets.

**Planning** **and Additional Analysis**    Technical Needs

**Notes:**
Moving to ZEB will require a significant accomplishments in both performance and cost.

## The optimization model presents additional benefits for assessing building technologies that typical simulation models do not offer.

- Future technologies accepted

**Results**

**Inputs**

**Optimization**

- Performance minimized
- Cost minimized
- Performance specified at onset

- Potential technology bundles defined

**Planning** **and Additional Analysis**    Additional Benefits

**The optimization model presents additional benefits for assessing building technologies that typical simulation models do not offer.**

## With its functionality, the optimization model will continue to support the development of technology pathways that will enable ZEH. 

**Planning** **and Additional Analysis**    Additional Analysis

- Further analysis will be used to evaluate new technologies as well as construction techniques ability to contribute to ZEH.
- Additional analysis will be used to identify the performance and cost requirements of the necessary control systems.
- As cost data becomes available, will continue to update and improve.

**Notes:**
Developing technologies provides the pathways for achieving net zero energy buildings, but the integration of these pathways is critical to reaching zero energy performance.  In order to reach extremely low levels of energy use and eventually zero energy use, a large number of complicated system-level or “whole building” interactions must be understood.  For example, lighting, appliance and plug or miscellaneous energy uses contribute to internal gains that offset heating loads in cold climates. New technologies that produce significant reductions of these uses will also produce a corresponding increase in heating energy use that must be considered as part of an overall system-based solution strategy.  With this in mind, research must go beyond just developing the technologies and begin to integrate these technologies in order to optimize the energy performance of the whole building.
Building integration could be achieved through a robust control system capable of monitoring, controlling and optimizing all energy flows both within and external to the dwelling in real time, which will provide unprecedented levels of energy performance, as well as, increased occupant comfort.  To reach levels of energy use near and at net zero, this control system will need to integrate structural, mechanical, and electric systems in a way that is also multi-functional, reliable, simple to use, and affordable.
The result of the optimization analysis portfolios demonstrates that while achieving Zero Energy Homes is possible, it will require significant research and development, particularly with regard to installed cost reduction.  As cost and performance of these technologies improve, the technology integration R&D tasks become increasingly critical to reaching the ultimate goal of net zero energy performance.  New tools will be needed as buildings become increasingly more efficient to integrate the buildings systems and to control them once they are constructed. 
Optimization was the first step in the whole building approach and further analysis will identify the performance and cost requirements of the necessary control systems.  With its functionality, the model will continually support the development of technology pathways and whole building integration tools that will enable zero energy homes.

## While achieving ZEH is possible, it will require significant research and development, especially with regard to installed cost.

**Planning** **and Additional Analysis** Conclusions

- As the cost and performance of these technologies improve, technology integration becomes extremely critical to reaching ZEH.
- In order to reach extremely low levels of energy use, a large number of system, or “whole building”, interactions must be exploited (I.e. combination appliances/equipment).
- Moving to large scale ZEH will require breakthroughs in renewable generation, and conservation technologies on both the performance and cost attributes.

**Notes:**
Developing technologies provides the pathways for achieving net zero energy buildings, but the integration of these pathways is critical to reaching zero energy performance.  In order to reach extremely low levels of energy use and eventually zero energy use, a large number of complicated system-level or “whole building” interactions must be understood.  For example, lighting, appliance and plug or miscellaneous energy uses contribute to internal gains that offset heating loads in cold climates. New technologies that produce significant reductions of these uses will also produce a corresponding increase in heating energy use that must be considered as part of an overall system-based solution strategy.  With this in mind, research must go beyond just developing the technologies and begin to integrate these technologies in order to optimize the energy performance of the whole building.
Building integration could be achieved through a robust control system capable of monitoring, controlling and optimizing all energy flows both within and external to the dwelling in real time, which will provide unprecedented levels of energy performance, as well as, increased occupant comfort.  To reach levels of energy use near and at net zero, this control system will need to integrate structural, mechanical, and electric systems in a way that is also multi-functional, reliable, simple to use, and affordable.
The result of the optimization analysis portfolios demonstrates that while achieving Zero Energy Homes is possible, it will require significant research and development, particularly with regard to installed cost reduction.  As cost and performance of these technologies improve, the technology integration R&D tasks become increasingly critical to reaching the ultimate goal of net zero energy performance.  New tools will be needed as buildings become increasingly more efficient to integrate the buildings systems and to control them once they are constructed. 
Optimization was the first step in the whole building approach and further analysis will identify the performance and cost requirements of the necessary control systems.  With its functionality, the model will continually support the development of technology pathways and whole building integration tools that will enable zero energy homes.