historic homes guide
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BUILDING TECHNOLOGIES PROGRAM
Energy Performance Techniques
and Technologies:
Preserving Historic Homes
BUILDING AMERICA BEST PRACTICES SERIESVOLUME 13.
PREPARED BY
Pacific Northwest National Laboratory
& Kaufman Heritage Conservation
February 28, 2011
R
February 28, 2011 PNNL-20185
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BUILDING AMERICA BEST PRACTICES SERIES
Energy Performance Techniques
and Technologies:
Preserving Historic Homes
PREPARED BY
Pacific Northwest National Laboratory
Michelle Britt, Michael C. Baechler,
Theresa Gilbride, Marye Hefty,
Erin Makela, and Elaine Schneider
and
Kaufman Heritage Conservation
Ned Kaufman, Ph.D.
February 28, 2011
Prepared for the U.S. Department of Energy
under Contract DE-AC05-76RLO 1830
PNNL-20185
This report was prepared as an account of work sponsored by an agency of theUnited States Government. Neither the United States Government nor any agency
thereof, nor Battelle Memorial Institute, nor any of their employees, makes any
warranty, express or implied, or assumes any legal liability or responsibility for the
accuracy, completeness, or usefulness of any information, apparatus, product, or
process disclosed, or represents that its use would not infringe privately owned
rights. Reference herein to any specific commercial product, process, or service by
trade name, trademark, manufacturer, or otherwise does not necessarily constitute
or imply its endorsement, recommendation, or favoring by the United States
Government or any agency thereof, or Battelle Memorial Institute. The views and
opinions of authors expressed herein do not necessarily state or reflect those of
the United States Government or any agency thereof.
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ENERGY PERFORMANCE TECHNIQUES AND TECHNOLOGIES PRESERVING HISTORIC HOMES
R
You can learn more about Building
America and download additional copies
o this document, other best practices,
research reports, and case studies at
www.buildingamerica.gov
Preface
This guide is a resource to help contractors renovate historichouses, while addressing issues such as building durability, indoor
air quality, and occupant health, saety, and comort. The best
practices described in this document are based on the results
o research and demonstration projects conducted by Building
Americas research teams. Building America brings together the
nations leading building scientists with over 300 production
builders to develop, test, and apply innovative, energy-efcient
construction practices.
Acknowledgments
The U.S. Department o Energys (DOEs) Building America
Program comprises public-private partnerships that conduct
systems research to improve overall house perormance, increase
housing durability and comort, reduce energy use, and increase
energy security or Americas homeowners.
Program activities ocus on fnding solutions or both new and
existing homes, as well as integrating clean onsite energy systems
that will allow the homebuilding industry to provide homes
that produce more energy than they use. In addition to DOEmanagement and sta, the Building America Program includes
15 consortia, our national laboratories, and hundreds o builders,
research organizations, manuacturers, and service providers.
The DOE Building America Program unded the development
o this guide. DOE also unded the Building America consortia
and national laboratories to conduct the research that orms the
basis or these recommendations. The consortia have taken on the
hard work o applied research, feld testing, training builders, and
transorming results into building practices. Numerous drawings,
descriptions, photos, and case studies originated with these research
partners. Examples rom these partners are used throughout this
guide to illustrate construction best practices.
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Contents
Preface ............................................................................................................................................................................i
Acknowledgments ....................................................................................................................................................i
1. Introduction............................................................................................................................................................1
2. Background: The Historic Building Context ........................................................................................3
Identification and Preservation of Historic Places...............................................................................4
Related Local and State Resources ............................................................................................................ 5
Building Codes ...................................................................................................................................................... 6
Preservation Project Classifications and Related Standards ......................................................... 7
3. Planning the Historic House Whole-House Energy Retrofit .......................................................9
The Energy Audit: A Vital Step in Retrofitting a Historic House ................................................ 10
Finding a Contractor to Retrofit a Historic House .............................................................................. 11
4. Historic House Upgrades ..............................................................................................................................12
Making the Most of the Potential of the Original Design ................................................................12
Air Sealing..............................................................................................................................................................13
Insulation Moisture Issues in the Attic and Basement ......................................................................15
Roofs.........................................................................................................................................................................16
Walls ..........................................................................................................................................................................18
Windows .................................................................................................................................................................19
Systems for Heating and Cooling a House ............................................................................................21
Lighting ..................................................................................................................................................................24
Other Considerations During an Energy Retrofit ..............................................................................25
Porches ...................................................................................................................................................................25
Landscaping and Siting ................................................................................................................................25
Seismic Retrofits ................................................................................................................................................26
5. Conclusion ...........................................................................................................................................................27
References.................................................................................................................................................................28
Appendix Health and Safety Concerns ................................................................................................30
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ENERGY PERFORMANCE TECHNIQUES AND TECHNOLOGIES PRESERVING HISTORIC HOMES
1. Introduction
The U.S. Department o Energys (DOEs) Building America
Program is an industry-driven research program that promotes the
accelerated development and adoption o advanced building energy
technologies in new and existing homes. The program gives home
builders and remodelers access to the nations leading building science
developments to build high-perormance homes that use less energy,
are more comortable, healthier to live in, and long lasting. This guide
is a resource or contractors and owners o historic houses who want
to improve the energy efciency while protecting historic character.
Although older buildings require attention and maintenance, they
repay the eort as assets that gain value over time. More and more,
homeowners value historic houses or their appealing aesthetic
character, liestyle advantages, and quality o lie. Depending on the
circumstances, these advantages may include beautiul ornamentation,
spacious room proportions, natural lighting, outdoor spaces, and
not least o alla eeling o history, tradition, and permanence.
Furthermore, time has shown that even the most unappreciated historic
styles eventually become popular; so, even i you have mixed eelings
about the appearance and design o a historic house, bear in mind
beore doing anything to diminish its historic character, that the next
occupants may love that styleand that may aect the selling price.
Special energy-retroftting challenges include preserving the homes
historic eatures, being aware o and adhering to regulations related
to historic designations, and addressing health and saety issues.
Building Americas research provides feld-tested approaches to help
address these challenges.
Sponsored by the U.S. Department
o Energy, the Building America
Program is industry-driven
research designed to accelerate
the development and adoption o
advanced building energy technologies
in new and existing homes (or more
inormation, see www.buildingamerica.gov.) Building Americas renovation
case studies illustrate proven
techniques applied to historic houses
in a variety o climates (or published
examples, see www.eere.energy.
gov/buildings/building_america/
climate_specific_publications.html).
Retrofitting homes that are designated
as historic may require a ormal
review process, but all homes deserve
a thoughtul approach to maintaining
their character.
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Retroftting homes that are designated as historic may require a
ormal review process, but all homes deserve a thoughtul approach
to maintaining their character. I you are a contractor, share this
guide with your clients so they can understand how you will make
their homes more comortable, durable, and energy efcient, while
respecting the homes historic qualities.
Following Building America-sponsored research, this document
ocuses on planning energy-efcient improvements or historic
houses by combining energy-efcient best practices with theprocess o historic renovation. The background or retroftting
and preserving older homes that may be designated as historic is
introduced. Steps to consider when planning a whole-house energy
retroft are highlighted. Strategies or maximizing the potential
energy efciency o an original house design and preserving its
character are presented. Aspects o retroftting a historic house
while preserving its character are addressed. Finally, the document
describes health and saety concerns related to past building
materials and practices. Reer to the resources cited throughout
this guide or additional inormation. This document does not
delve into the details o installation techniques. These practicesvary depending on construction materials, methods, and climate
zones, but reerences are provided so readers can access
installation inormation.
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2. Background:
The Historic Building Context
Improving energy perormance using Building Americas quality-
management practices and whole-house energy approach helps
deliver more energy-efcient and durable historic houses. The
historic nature o a home requires additional thought and sensitivity
to its construction and design eatures. When contemplating a historic
house remodel, it is important to determine whether there is any
possibility the property may be historically signifcant. Contact the
local building and planning departments to inquire about a local
historic preservation ordinance and whether:
THE HOME IS ELIGIBLE FOR LISTING IN THE
NATIONAL REGISTER OF HISTORIC PLACES
THE PROPERTY IS LOCATED WITHIN A HISTORICNEIGHBORHOOD OR DISTRICT
ANY LOCAL OR STATE HISTORIC ORDINANCES APPLY.
Understanding the regulatory requirements or preserving the
character-defning eatures o the home is as important as assessing
the homes inherent energy-conserving potential. It is important
to improve historic houses through maintenance, upgrading, and
environmental retroftting, but do not destroy its historic abric
and regret it later.
Because eective retroftting considers the historic character o ahome and the materials used to construct it, the builder may need
to coner with a historic preservation consultant. The State Historic
Preservation Ofce and local historic preservation ofce, society, or
commission may be able to identiy preservation design consultants
and restoration contractors who have experience with similar
projects. As preservationists, they want to preserve historic structures
rom demolition or degradation. They can help determine how to
best blend retroftting additions with the existing decorative details
and historic eatures o the home without damaging its character.
Builders need to be amiliar with the identifcation and preservation
o historic houses, related state and local resources, how codes might
aect retroftting, and any ederal permitting issues. I working with
preservationists on the project team, they also need to share a common
language as they work together to assess, plan, and decide how to
retroft the home. This section provides an overview o these needs.
www.nps.gov/nr/publications/index.htm
A good reerence or anyone
considering working with a historic
house is the National Register
Bulletin 15, How to Apply the
National Register Criteria for
Evaluation, which is available both
in print and online (http://www.nps.
gov/nr/publications/bulletins/nrb15/ ).
The National Park Service also
developed The Secretary o the
Interiors Standards or the Treatment
o Historic Properties with Guidelines
or Preserving, Rehabilitating,
Restoring, and Reconstructing
Historic Homes (hereater Secretarys
Standards; see www.nps.gov/history/
hps/tps/standards_guidelines.
htm). These standards and design
guidelines have been adopted by
state preservation agencies and
by many local ordinances and
programs (see www.energysavers.
gov/your_home/energy_audits/
index.cm/mytopic=11160 and http://
apps1.eere.energy.gov/buildings/
publications/pds/building_america/
ba_airsealing_report.pd).
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The [National Register]criteria do not describeexceptional, nor should they.
Exceptional, by its own definition,
cannot be ully catalogued or
anticipated. It may reflect the
extraordinary impact o a political or
social event. It may be a unction o
the relative age o a community and its
perceptions o old and new. It may be
represented by a building or structure
whose developmental or design value
is quickly recognized as historically
significant by the architectural or
engineering proession. It may be
reflected in a range o resources orwhich a community has an unusually
strong associative attachment.
For more inormation go to
www.nps.gov/history/nr/publications/
bulletins/nrb22/nrb22_I.htm
Identification and Preservation of Historic Places
The National Register o Historic Places (NRHP or National
Register)a division o the National Park Service (NPS)is
the authority on the topic o historic buildings. According to
the National Register criteria, homes over 50 years old may beconsidered historic i they were designed by a master architect,
have high aesthetic value, typiy a style or type o construction,
or are associated with signifcant individuals or historic trends.
In particular, the National Register criteria (www.nps.gov/nr/
publications/bulletins/nrb15/nrb15_2.htm) or evaluation o
historic sites state that:
The quality o signifcance in American history, architecture,
archaeology, engineering, and culture is present in districts, sites,
buildings, structures, and objects that possess integrity o location,
design, setting, materials, workmanship, eeling, and association, and:
THAT ARE ASSOCIATED WITH EVENTS that have made a
signifcant contribution to the broad patterns o our history; or
THAT ARE ASSOCIATED WITH THE LIVES o signifcant
persons in or past; or
THAT EMBODY THE DISTINCTIVE CHARACTERISTICS
o a type, period, or method o construction, or that represent
the work o a master, or that possess high artistic values, or
that represent a signifcant and distinguishable entity whose
components may lack individual distinction; or
THAT HAVE YIELDED OR MAY BE LIKELY TO YIELD
INFORMATION important in history or prehistory.
Homes under 50 years old can also be considered historic, but
they must have exceptional signifcance, with exceptional
reerring to the recognition o locally signifcant historic resources
that, by appearance or association with persons or events, provide
communities with a sense o past and place.
Homes located in historically designated neighborhoods must ollowthe requirements o the district even though specifc homes may not
meet the National Register criteria or eligibility.
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Related Local and State Resources
Beore making any energy improvements on a historic house, it is
important to ully understand the local, state, and ederal rules and
regulations that may govern changes to the historic house. Resources
or this inormation will vary by community, but start by contactingthe local building department, planning department, or historic
preservation ofce, society, or commission.
Although the criteria or defning historic may have been
developed by a ederal agency, it is most oten a local ordinance
that aects a project. I the jurisdiction has adopted by ordinance a
historic district, neighborhood, or a listing o historic houses, there
will be design guidelines to ollow, and a review board may need to
evaluate and approve the project beore a building permit may be
issued. The design review may carry extra costs that the contractor
or owner needs to actor into the budget.
For example, Eureka, Caliornia, originally settled in the mid-to late
1800s, has a heritage rich in lumber history, as is reected in its stock
o historic houses. I you were considering a project on an existing
home in Eureka, a call to the building or planning department (or
visit to its website: www.ci.eureka.ca.gov/depts/cd/permits_n_orms.asp)
would provide you with the Historic Preservation Ordinances
administered by the planning department. The inormation ound on
the website would tell you the Historic Preservation Commission is
responsible or the ollowing:
MAINTAINING A LIST OF LOCALLY, REGIONALLY, AND/OR
NATIONALLY SIGNIFICANT PROPERTIES AND DISTRICTS
called the Local Register o Historic Places.
HAVING AUTHORITY TO REVIEW APPLICATIONS
or additions, alteration, new construction, or demolition o all or
part o any structure, or landscape element (such as historic walls
and trees designated in the Historic Preservation Application) that
is located on a property listed in the Local Register o Historic Places.
HAVING THE AUTHORITY TO REVIEW AND MAKE
DECISIONS or all requests rom property owners to haveproperty placed in, or removed rom, the Local Register
o Historic Places (City o Eureka, Historic Preservation
Packet_2010).
The Magdalena Zanone House
Photo by Ron Kuhnel
The federal government does
not monitor the renovation
of privately funded historic
buildings. All regulations directly
afecting the project can be ound at
the local and state levels.
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A states SHPO contact inormation
can be ound through the National
Conerence o State Historic
Preservation O cers
(www.ncshpo.org/find/index.htm#top).
Regional and local guides will provide
inormation specific to the climate and
building materials o your region.
Be sure to confirm whether
local or regional design guides
exist; these will address local
climate conditions, locally specific
building methods and construction
practices over time, and oten local
building materials. For example, the
Sustainable Solutions or Historic
Houses in Northern Caliornia (www.
epa.gov/brownfields/sustain_plts/
reports/green_home_guide_final.pd),
addresses local climate issues and the
extensive use o redwood.
A resource for information
on building energy codes is
www.energycodes.gov.
I the planning or building department in your community uses a
similar approach, veriy whether the property in question is listed
and determine the associated process or application submittal,
review, public hearing, and decision by the commission prior to
being granted a building permit. Any or all o these steps will aect
the budget and design process.
As noted earlier, the ordinances that aect your project will be local,
but they oten rely on the Secretarys Standards or the treatment
o historic properties and guidelines or preserving, rehabilitating,
restoring, and reconstructing historic houses. In the Eureka,
Caliornia example, the review process includes a review o the
project to ensure consistency with the Secretarys Standards. Other
jurisdictions have developed their own standards you will need to
work with.
In addition to being aware o local restrictions, contact the StateHistoric Preservation Ofce (SHPO) to determine whether specifc
historic preservation design guidelines have been developed or your
state. The SHPO will also have inormation about any historical
surveys that have been completed or signifcant issues that have been
raised regarding the property you are considering renovating, and
can provide guidance in determining appropriate local resources.
Building Codes
Building permits may be required or energy improvements, and
the historic nature o the project may aect how the local buildingcodes apply to the project. The local code ofcial will provide
inormation about which codes have been adopted, and how
they are enorced relative to historic properties. For example, the
International Residential Code (IRC), which regulates construction
o single-amily houses, two-amily houses (duplexes), and buildings
consisting o three or more townhouse units, has been widely
adopted by jurisdictions nationwide.
The International Energy Conservation Code (IECC) has also
been widely adopted, and, like the IRC, it applies to building
additions, alterations, and repairs. However, as Section 101.1.2 o
the 2009 IECC states, properties that are listed, locally designated
as historic, or or which an opinion has been granted that it is
eligible to be listed are exempt rom the IECC. This is particularly
important when considering energy retroft projects, such as
windows and insulation.
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Historic Rehabilitations
Some jurisdictions have also adopted the International Existing
Building Code (IEBC), which is specifc to the use and reuse o
existing buildings, both residential and commercial, with Chapter 11
being specifc to historic buildings. It can be adopted by jurisdictions
as a means to codiy exceptions or historic buildings, and it can be
used in historic districts. An important distinction is that the IECC
excludes properties that could be listed, while the IEBC in general
applies to all historic properties (IEBC Chapter 11, Historic Buildings,applies only to listedproperties). I your jurisdiction has adopted
the IEBC, it is important to clariy which code will apply to your
project, because the IEBC, IECC, and IRC interace and overlap.
Preservation Project Classifications
and Related Standards
While contractors, building ofcials, and codes classiy projects as
additions, alterations, or repairs, depending on how extensive the
work is, preservationists typically classiy projects as preservation,
rehabilitation, restoration, or reconstruction, based on the goals
o the project and resulting impacts on the historic integrity o the
building. Beore the project begins, decisions need to be made about
how the property will be used, and i there are historic eatures that
can be retained. The National Park Service provides defnitions to
help determine the project classifcations. Note that additions and
alterations are both considered rehabilitation.
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The National Park Serviceidentifies five examplesto help illustrate theseclassifications.
Preservation Jacksonville NationalHistoric District (www.nps.gov/history/
hps/workingonthepast/case_studies/
jacksonville1.htm).
Rehabilitation 1 Baker Historic
District (www.nps.gov/history/hps/
workingonthepast/case_studies/
bakercity1.htm).
Rehabilitation 2 Ladds Addition
Historic District(www.nps.gov/history/
hps/workingonthepast/case_studies/
laddsaddition1.htm).
Restoration Monteith Historic
District (www.nps.gov/history/hps/
workingonthepast/case_studies/
monteith1.htm).
Reconstruction Oswald West
Coastal Retreat (www.nps.gov/history/
hps/workingonthepast/case_studies/
oswaldwest1.htm).
PRESERVATION ocuses on the maintenance, stabilization, and
repair o existing historic materials and retention o a propertys
orm as it has evolved over time. The historic eatures o the home
are not limited to one time period.
REHABILITATION acknowledges the need to alter or add to
a historic property to meet continuing or changing uses whileretaining the propertys historic character.
RESTORATION depicts a property at aparticular periodo time
in its history, while removing evidence o other periods. Restoring
a home is signifcantly dierent rom preserving or rehabilitating
it; less exibility is allowed in modernizing the building and
mixing elements rom various time periods. All modern changes to
the house are removed so that only one period is interpreted.
RECONSTRUCTION re-creates vanished or non-surviving
portions o a property or interpretive purposes. While houses asa whole arent typically reconstructed, independent elements o a
home, i.e., chimneys, porches, and so orth, can be and oten are
reconstructed.
It is important or contractors and homeowners to know how
to historically categorize their project, because the local or
state ordinance may base the design review o the project on
this classifcation and the applicable design guidelines rom the
Secretarys Standards.
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3. Planning the Historic House
Whole-House Energy Retrofit
Armed with inormation about any local ordinances or resources
and applicable building codes, planning or the retroft can begin.
Dont orget that, as old-ashioned as it may seem, a historic house
actually may have some environmental advantages that would be
hard to duplicate now: high-quality timber and windows, non-toxic
interior materials, heat-retaining masonry walls, mature shade trees,
through-ventilation, natural lighting, and so orth. Make these the
basis o your environmental retroft. But most o all, remember that
the mere act the house exists represents an environmental plus: you
dont have to build a new one! By retroftting the old one instead o
demolishing and building new, you are saving valuable materials,
reducing the amount o waste going into the landfll, andabove
allreducing carbon use and greenhouse gas emissions. As an addedbonus, you are enhancing the character o your community.
With these advantages in mind, consider how the retroft o the
historic home will dier rom retroftting a more contemporary
home. As with their modern counterparts, historic houses operate
as systems, but they work dierently rom contemporary homes,
and the systems vary depending on the era and style o architecture.
Understanding how these systems work and diagnosing their
needs are important steps in retroftting historic houses. Using an
integrated design approach is just as important in retrofts as it is in
new construction.
Building Americas systems approach to home design acknowledges
that as buildings become increasingly efcient, the interactions o
all o the homes components and subassemblies must be taken
into account to maximize perormance and avoid unintended
consequences. This whole-building approach recognizes that
changes in one or a ew components can dramatically change how
other components perorm, thereby aecting the overall building
energy use, comort, and durability. The integrated design process
used to improve the homes efciency and perormance can also be
applicable to remodeling and preserving historic houses.
Whole-building design suggests that a single change in a homes
structure or other systems can aect the rest o the home.
A key idea behind integrated
planning is that decisions about all
building systems, including equipment
selection, sizing, and placements,
are made within the design process,
not as aterthoughts in the field. The
decisions are made with the help o
analytical tools and the input o all
relevant disciplines. Rather than a linear
traditional process, the integrated
process involves looping in ongoing
input rom relevant sources.
The REGREEN Program is a
partnership between the American
Society o Interior Designers and U.S.
Green Building Council. The remodeling
guidelines address sustainable
remodeling practices and have been
applied to historic houses.
(www.regreenprogram.org).
42,226 homes have been built to
date using technologies and strategies
developed through Building America
research to construct high-quality,
energy-ef cient homes (http://apps1.
eere.energy.gov/buildings/building_
america/cm/project_locations.cm).
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Sealing air leaks may result in a need
or ventilation.
Experienced auditors or HVAC
contractors will conduct computer
simulationsACCA Manual J runsto
determine the how large the urnace
and air conditioner should be, based on
their inspection and findings.
For example, adding insulation and sealing air leaks can improve the
energy efciency o a home and improve its comort and durability.
However, every change made to the buildings envelope (walls, oors,
and ceiling) will aect the perormance, health, and saety o the
house. Sealing air leaks in the building envelope without providing
appropriate ventilation can cause pressure imbalances or negative
pressure inside the house. This negative pressure can cause freplaces,
urnaces, or other uel-burning appliances to release dangerous umes
into the house instead o exhausting them through chimneys or ues.
A home energy audit is conducted to help understand how a historic
house operates as a system and diagnose its particular needs. As
described below, a certifed contractor or auditor conducts the
audit and understands how historical systems work together to
keep a house operating as it should, and how changes will aect the
whole system.
The Energy Audit:
A Vital Step in Retrofitting a Historic House
Whole-house energy audits and inspections typically do the ollowing:
ASSESS how much energy the home consumes.
DETERMINE what measures to take to make the home more
energy efcient.
EVALUATE whether basic health and saety criteria are met.
The audit should be conducted by a certifed proessional, preerably
one with experience working with older homes and historic
preservation issues. (See the next section or how to fnd a certifed
auditor.) The auditor should frst confrm whether the National
Register has listed the home as a historic building. The audit will
then identiy problems that may, when corrected, save signifcant
amounts o money and energy over time. It will pinpoint where the
house is losing energy and determine the efciency o the homes
heating and cooling systems. The audit may also identiy ways to
conserve hot water and electricity.
A proessional auditor uses a variety o techniques and diagnostic
equipment to measure how a house perorms in ways that cannot
be seen by eyes alone. These tests may include a blower door test to
determine air leakage and house pressurization problems, tests to
detect drats and the eectiveness o the ducts, combustion saety
testing, and carbon monoxide sampling.
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The auditor will also estimate the costs o making various
improvements and will use a computer program to estimate the
annual savings expected rom each improvement. The cost o the
measures divided by the annual savings will provide the simple
payback or how many years the measures will take to pay or
themselves. Some energy measures may be as simple as stopping
unwanted heat transers by tightening leaky windows and doors.
Addressing the simple fxes will reduce the number o big-ticket fxes
needed. As experienced energy auditors know, or big-ticket fxes,
like new urnaces, it is important to weigh all o the available options
and install the smallest system needed.
The recommended energy-saving improvements derived rom
the audit results must be weighed against their impacts on the
historic character o the home and associated regulations, and any
retroftting decisions must take into account the unique costs o
historic house, such as custom windows. Note, the cost built into astandard audit may not capture the customized work needed or a
historic house.
More importantly, historic houses may contain open-combustion
appliances, such as gas-burning urnaces that use the air in the room
or the uel-burning process. Saety problems o open-combustion
appliances can be exacerbated when retroftting a home. When
cracks and leaks that once let in air are sealed, carbon monoxide and
air pollutants rom cleaning chemicals, combustion appliances, and
o-gassing household products can build up, creating an unhealthy
and even dangerous environment in the home.
These older homes also may have dry rot and moisture problems.
A certifed contractor ollows an auditing process that ensures
that any health, saety, and moisture problems are solved during
the whole-house energy retroft. With ongoing attention to the
homeowners health and saety, the contractor also identifes any
potential problems related to historically used materials, such as lead
and asbestos, that can cause major health problems (see Health and
Saety Concerns in the Appendix).
Finding a Contractor to Retrofit a Historic House
There are two nationally recognized energy certifcations or home
energy auditors and contractors: the Building Perormance Institute,
Inc. (BPI) Building Analyst certifcation and the Residential Energy
Services Network (RESNET) Home Energy Rating System Rater
certifcation. To date, BPI certifcation has ocused on understanding
the building science o retroftting existing homes, and BPI will
Atmospheric combustion
For more information about
home energy assessments and air
sealing, see www.energysavers.gov/
your_home/energy_audits/index.
cm/mytopic=11160 and the Building
America air sealing document (http://
apps1.eere.energy.gov/buildings/
publications/pds/building_america/
ba_airsealing_report.pd).
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Shutters and awnings
be the best resource or historical home energy audits. BPI is a
nonproft organization that accredits auditors, contractors, and
other building proessionals. Auditors or building analysts specialize
in evaluating building systems and potential energy savings in
homes. The certifed BPI Building Analyst energy auditor has passed
both written and feld exams, and must recertiy every 3 years.
Contractors learn about building systems and are trained to install
energy-efciency measures. For more inormation about BPIs
standards and credentials or retroftting work, see www.BPI.org.
A certifed proessional home inspector who has experience working
with historic houses can be ound by contacting the local historical
society or suggestions. The Historic Building Inspectors Association
is another excellent resource depending on its availability in your
local area (also see http://inspecthistoric.org).
4. Historic House Upgrades
Improving energy efciency in a historic house involves paying
careul attention to how to make the most o its original design
eatures , ensuring the durability o the home, and preserving the
homes character during the remodel.
Making the Most of the
Potential of the Original Design
Building Americas research clearly indicates that climate zones aect
building and retroftting decisions. For example, radiant barriers are
not recommended in cold climates because o the moisture problems
they can cause. Historic builders intuitively understood some o these
climate-specifc eatures, and most o the eatures should be retained
during the energy retroft. For example, builders oten incorporated
eatures into the site and building design that helped moderate interior
temperatures or provided or comortable outdoor living areas
eatures like operable windows, awnings, heat-retaining masonry
walls, high ceilings, through-ventilation, shade trees, and so orth.
These eatures are still the basis o good design, and contemporary
homeowners will beneft rom maximizing their potential in terms ocomort or energy savings, while also retaining the historic character
o the home. The National Trust or Historic Preservation (NTHP)
identifes the ollowing historically useul cold and hot climate eatures
(also see www.preservationnation.org):
SHUTTERS AND AWNINGS used in both hot and cold climates,
with adjustable louvers allow or air circulation and block solar
gain on hot days. Operable shutters reduce drats on colder days
and block solar gain on hot days. Post-Katrina construction in
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New Orleans and on the Gul Coast is seeing the reinstitution o
more historic louver shutters that admit air, while providing shade.
Removable or permanently attached awnings protect the windows
rom solar gain on hot days, allowing or winter solar gain.
OVERHANGS, EAVES, AND COVERED PORCHES provide
shaded outdoor living space and protect the walls rom the hotsummer sun and precipitation. I siding is being replaced, an
overhang could allow or the addition o exterior rigid oam to
help insulate the walls.
SEASONALLY SHADED INTERIOR COURTYARDS provide
outdoor living space or hot summer days and warm protected
areas on cooler days.
BRICK AND ADOBE provided thermal mass to moderate the
temperature swings, releasing heat gained during the day into the
cooler night.
CROSS VENTILATION is encouraged with the use o double-
hung windows both upstairs and downstairs, creating an air ow
through the house and exhausting hot air rom the upper story.
VEGETATION is used to provide windbreaks and provide shade
or the hot summer days. Evergreen trees provide year-round wind
protection while deciduous trees provide seasonal shade, allowing
or winter solar gain.
Taking advantage o retaining these eatures will beneft the
home by preserving its historic integrity, increasing the comorto the homeowners, and reducing the need or additional energy
efciency eatures.
Air Sealing
Whether a home is located in a hot and dry or very cold climate, one
o the least expensive and potentially most eective energy-retroftting
measures is air sealing. The Building Americas Best Practices Guide,
Air Sealing: A Guide or Contractors to Share with Homeowners (http://
apps1.eere.energy.gov/buildings/publications/pds/building_america/
ba_airsealing_report.pd), provides comprehensive guidance or air
sealing existing homes. The guide helps identiy ways to make homes
more comortable, more energy efcient, and healthier to live in.
It also identifes the steps to take to seal unwanted air leaks while
ensuring healthy levels o ventilation and avoiding sources o indoor
air pollution. Studies show that air-sealing measures described in the
guide can typically achieve whole-house energy savings o 10% to 20%
over pre-retroft energy usage. In older homes or homes with greater
air leakage, the savings may be much greater.
Miller placed rigid oam insulation and
a new three-coat stucco finish over the
original adobe walls but kept the historic
masonry parapet visible to retain the
homes southwestern character.
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The Building America Asdal case study
illustrated the use o rigid oam sealed in
place with spray oam to insulate the band
joists (top) and the use o spray oam
around piping and wiring holes (www.eere.
energy.gov/buildings/building_america/
cold_case_studies.html).
Establishing the continuity o the air barrier system o a building
is the goal o air sealing, which should be an integral part o all
aspects o the retroft rom roo to cellar to window repair. However,
it is important to remember the building is unctioning as a system,
and all parts o the system must work together to keep moisture
rom causing damage to the structure or being a health hazard to the
occupants. As an air quality issue, the growth o mold and mildew
may be exacerbated by the reduction in air leakage, but air sealing
in general does not inhibit drying o the structure, unless it results in
encapsulating the structure with vapor-impermeable material. Mold
and mildew growing in moist areas may cause allergic reactions
and damage building materials. I the air movement through the
structure was allowing parts o the structure to dry out, sealing the
building may require the addition o mechanical ventilation.
Two key examples o air sealing in historic houses and approaches
taken to avoid indoor air quality problems are described below.
Pittsburgh Depression Era Bungalow
The Building America Asdal Builders, LLC Pittsburgh Case Study
(Pittsburgh; http://apps1.eere.energy.gov/buildings/publications/pds /
building_america/ba_cs_retroft_asdal_builders.pd) demonstrates
the way one change can trigger another in the house as a system.
The renovators caulked the sill plates, air sealed the unfnished
basement walls, and sealed the band joists with spray oam and
rigid oam insulation. The extensive air sealing provided a very
tight house, demonstrated by blower door tests. However, the tight
house necessitated another stepproviding adequate combustionair. The natural gas boiler used combustion air drawn rom inside
the home, thereby drawing oxygen rom the living environmenta
health concern in tightly sealed homes. The solution was to install a
new boiler, with power venting drawing combustion air rom the
outside.
Newburgh 18th Century Brick
The Building America Habitat or Humanity, Newburgh, NewYork
Case Study (Habitat Newburgh; http://apps1.eere.energy.gov/
buildings/publications/pds/building_america/ba_cs_retroft_
newburgh_habitat.pd) illustrates how to handle historical elements
that are also air leakage problems. The goal was to reach a fnal
infltration rate o 0.60 air changes per hourthe ENERGY STAR
requirement or new homes. The freplace contributed to the air
leakage, but was a historical element o the home. The solution was
to close o the freplace and careully seal around it, but retain it as
a decorative element or its historical value.
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When air leakage is signifcantly reduced, mechanical air ventilation
may be necessary. American Society o Heating, Rerigerating and
Air-Conditioning, Inc. (ASHRAE) Standard 62.2 or ventilation
and acceptable indoor air quality in low-rise residential buildings
provides the related standards and guidelines (ASHRAE 2007).
Installing ENERGY STAR exhaust ans on timers can provide
adequate ventilation.
Insulation Moisture Issues
A second key energy-saving practice or existing homes is installing
increased insulation in basements, above-grade walls, and attics. The
energy audit will have provided inormation about air leakage, moisture
issues, and desired insulation levels. Attic and basement insulation,
in particular, can increase the energy efciency o a home without
damaging its historical integrity, and the installation o insulation oten
can occur without aecting architectural eatures or details. However,altering the air-sealing and thermal properties o attics and basements
can result in signifcant moisture issues. DOEs Building Technologies
Program Insulation Fact Sheet (www.ornl.gov/sci/roos+walls/
insulation/ins_06.html) describes the issue as ollows:
When moist air touches a cold surace, moisture may orm as
condensation. I moisture condenses inside a wall, or in your attic,
you will not be able to see the water, but it can cause a number o
problems. Adding insulation can either cause or cure a moisture
problem. When you insulate a wall, you change the temperature
inside the wall. That can mean that a surace inside the wall, suchas the sheathing behind your siding, will be much colder in the
winter than it was beore you insulated. This cold surace could
become a place where water vapor traveling through the wall
condenses and leads to trouble. The same thing can happen within
the attic or in a crawlspace or basement. With careul design the
new temperature profle could prevent condensation and help keep
your walls or attic drier than they would have been.
Massachusetts 1760 Cape
Basement walls may have historical signifcance, contributing to the
difculty o adding exterior insulation. Basement walls, typically
ound in colder climates, can present other specifc challenges as
demonstrated in The Building America National Grid Deep Energy
Retroft Pilot Program: Clark Residence, Belchertown, Maine (Clark
Residence; www.buildingscience.com/documents/case-studies /
cs-ma-ngrid-deep-energy-retroft?topic=resources/retrofts ). Prior
to the retroft, there were occasions o standing water in the
Clark Residence basement. Trenching, piping, and gravel mitigated
For more information on air
sealing, reer to Building Americas Best
Practices Guide, Air Sealing: A Guide or
Contractors to Share with Homeowners
(http://apps1.eere.energy.gov/buildings/
publications/pds/building_america/
ba_airsealing_report.pd).
In the Clark Residence, the
basement is conditioned with 3 to
5 inches medium-density spray oam
insulation applied directly to field
stone and concrete oundation walls.
Spray oam insulation is painted with
ignition barrier paint. A 12-inch-high
strip o 2-inch oam insulation at the
slab edge provides a thermal break
and allows oundation walls to drain to
the sub-slab drainage system. Several
trenches with drainage pipes and filled
with gravel carry bulk water to drain.
The new cast concrete basement floor
slab is installed over 6-mil poly, 2-inchoam insulation, and a continuous bed
o gravel.
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The Building America New Bedord
Farmhouse case study illustrates significant
energy retrofits while maintaining thehistoric character o the building
(www.buildingscience.com).
The National Trust for Historic
Preservation oers guidance inweathering roos o historic houses
(www.preservationnation.org/issues/
weatherization/roofing/).
the drainage. The retroft solved a potential condensation problem
on the slab and walls by insulating with 3 to 5 inches o medium-
density spray oam applied directly to the feld stone and concrete
oundation walls and adding a gravel base, a vapor barrier, and rigid
insulation beneath the new slab.
Roofs
A leaky roo will set the stage or damage, decay, and potential
health and saety issues in a house. Repairing a leaky roo can
provide an opportunity to add insulation. The energy audit and roo
inspection should provide the inormation needed to determine the
perormance o the roo, identiying repair needs or the potential or
increasing insulation levels. The audit should answer key questions,
like those o the NTHPs Start with the Roo A Guide to Keeping
Weather Tight (www.preservationnation.org/issues/weatherization/
roofng/additional-resources/nthp_roofng.pd):
Is my roo energy efcient?
How do I know i my roo is ailing?
What type o roo orm is on my building?
When replacing my roo, do materials matter?
In addition to answering these questions, when planning to re-roo
consider how the pitch and materials o the roo distinguish its
historical period and character. In a historic house, the overallshape, pitch, and construction o the roo, as well as its raming
members may also have historic quality, because o the materials or
construction methods used. These elements may limit the available
options or adding insulation or other improvements.
Examples o reducing energy use by air sealing and insulating the
roos o historic houses are described below.
Massachusetts Mid-19th Century Farmhouse
The Building America Bedord Farmhouse High-Perormance
Retroft Prototype (Bedord Farmhouse; www.buildingscience.com/documents/case-studies/cold-climate-bedord-armhouse-retroft
case-study), demonstrates massive energy use reductions in a type
and age o building that is widespread in the region. The project
also demonstrates the application o specifc high perormance
techniques to an older building. By respecting and maintaining
the historic character o the building and elevating its aesthetics,
the project also allays concerns that a high perormance retroft
threatens the character and appeal o a neighborhood.
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The 150-year-old Bedord Farmhouse is located in the Building
America Cold and Very Cold Climate Zone, which necessitates
signifcant improvement o the insulation levels. The solution
or this structure was to seal and insulate the attic and basement
as conditioned spaces. The attic was unvented, and oil-aced
polyisocyanurate insulating sheathing was placed on top o the
existing repaired roo sheathing, while unaced fberglass batt
insulation was placed in the raters. The resulting R-56 insulation
contributed to an overall estimated 35% reduction in energy use
over the Building America benchmark and an estimated annual
savings o $930.
Tucson Adobe
The Building America John Wesley Miller Company renovation
o a historical adobe home in Tucson (Adobe renovation; http://
apps1.eere.energy.gov/buildings/publications/pds/building_america/
ba_cs_retroft_john_wesley_miller.pd) grappled with a very dierentclimate and roo type. Located in the Building America Hot and
Dry Climate Zone, the home has a traditional at roo design,
which required a dierent solution in energy retroftting. In this
case, the original roofng was removed rom the at roo assembly,
but the raming and plywood sheathing were retained. Two inches
o polyisocyanurate rigid insulation (R-13) were installed on top o
the sheathing, ollowed by a new built-up roo, which was painted
reective white or solar reectance in the hot and sunny climate.
Florida Victorian
The Florida Solar Energy Center (FSEC) dealt with the issue
o historic raming in its restoration case study o the Williams
home in Cooling Load Reduction and Air Conditioner Design
in a 19th Century Florida House Museum (Williams House; see
Chasar [2004] available at www.sec.uc.edu/en/publications/pd/
FSEC-CR-1508-05.pd). One o the project goals was to reduce the
cooling loads o the house, which necessitated the addition o attic
insulation. Although spray polyurethane oam products applied to
the roo deck would have provided both air sealing and insulation,
it would have hidden part o the historical eatures o the house and
the decision was made to add insulation at the ceiling level instead.
As exemplifed by the case studies, roofng solutions or energy
retrofts will vary with the climate zone, roo construction, and
historic details o the home.
(Top) The Building America New Bedord
Farmhouse case study sealed and insulated
the attic as a conditioned space, placing
oil-aced polyisocyanurate on top o theexisting repaired roo. Building Science
Corporation. 2010. Bedord Farmhouse
High Perormance Retrofit Prototype
(Case Study), (www.buildingscience.com),
Somerville, Massachusetts.
(Bottom) Blown-in insulation can be used
to dramatically increase insulation values.
Another resource for historicroof projects is the 1978 NPS
Preservation Brie 4: Roofing or
Historical Buildings (www.nps.gov/
history/hps/tps/bries/brie04.htm).
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(Top) The Building America Chesapeake
Habitat or Humanity case study
demonstrates a solution or brick walls:
installing rigid insulation between bricks
and raming, air sealing, and filling the new
cavity with batts (www.eere.energy.gov/
buildings/building_america/mixed_humid_
case_studies.html).
(Middle/Bottom) The Building AmericaSEER case study in New Jersey
demonstrated the use o blown-
in and oamed insulation under the
siding (http://apps1.eere.energy.gov/
buildings/publications/pds/building_
america/36474.pd).
Walls
Walls can be sources o air and moisture leaks, and in historical
homes they may be uninsulated. In addition to air sealing, an
energy retroft will seek opportunities or increasing the insulation
levels o exterior walls. However, insulating walls in historic housescan be challenging.
Chesapeake Habitat for Humanity
The Building America Chesapeake Habitat or Humanity Baltimore,
Maryland Case Study (Chesapeake Habitat; http://apps1.eere.energy.
gov/buildings/publications/pds/building_america/ba_cs_retroft_
chesapeake_habitat.pd) developed a solution or insulating brick-
walled homes. The technical directors on the projectSteven Winter
Associateswere seeking a solution to the thermal bridging that was
occurring when raming inside the above-grade walls and flling the
cavities with fberglass batts. Their R-21 wall solution was to install a1/2 inch o rigid insulation between the bricks and stud raming, air
seal the edges and gaps with oam, and then fll the new interior stud
wall with R-19 batts. The existing gap between the double brick wall
allowed or ventilation, so moisture did not penetrate to the oam.
New Jersey 19th Century
The Building America Strategies or Energy-Efcient Remodeling
2003 retroft in rural New Jersey (Drumheller and Wiehagen 2004;
http://apps1.eere.energy.gov/buildings/publications/pds/building_
america/36474.pd) demonstrates solutions or a dierent set o
issues. In this case, a 19th century home had uninsulated 2x4 walls,
with wood siding and partial interior sheathing. However, the siding
had deteriorated and needed to be replaced. The case study shows
that based on the existing wall conditions, two wall cavity insulation
choices were availablethe use o blown-in insulation materials or
oam-in-place insulation. Blown-in and oamed insulation materials
provide more o an opportunity to completely fll irregular wall
cavities and may be installed through small openings in the raming
bay. They also are particularly adaptable to insulating wall sections
that have coverings on both the exterior and interior o the raming
members. Additional insulation on the exterior o the raming wasalso considered because the siding was being replaced. The Building
America partners ultimately chose blown and oamed insulation in
the wall cavity and sheet insulation under the siding.
Another option or wood-clad buildings is the drill-and-fll
method o opening 2-inch holes and injecting fberglass or cellulose
insulation into the cavity, resulting in an R-13 to R-21 insulated wall,
depending on the cavity depth and type o insulation.
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Windows
The energy audit will have identifed moisture and/or air leakage
around windows and any other problems that exist with the current
windows. Window treatments may include the ollowing:
air sealing, ashing, and weatherstripping
repair and reconstruction
addition o storm windows
replacement with historically accurate replicas
replacement with wood windows o similar design (e.g., replacing
double hung with double hung outftted with similar material).
Which option is best suited to the project depends on the results o
the energy audit, climate, and the project objectivespreservation,
rehabilitation, or restoration. Because o the highly visible nature
o windows and their direct bearing on the historical integrity o
the building, the NTHP promotes rehabilitating existing windows
whenever possible. I there is water damage to the sills or around
the window, evaluate whether the window needs resetting with an
improved drainage plane.
As noted earlier, it is important to frst maximize the inherent
potential o the house to be energy efcient. Existing awnings or
shutters that provide appropriate shading, serve to ventilate the
(Left) Drill-and-fill wall insulation on a
house located in a Portland, Oregon histori
district. Typically narrow strips o siding are
removed beore drilling, and sealed holes
are hidden when siding is reinstalled.
(Right) Blown-in insulation can be installed
in walls rom the interior. Care must be take
to match existing wall finish textures.
The window may not be
the problem, but the installation
may be. The Building Science
Corporation, in Building Science
Digest-105: Understanding Drainage
Planes (https://www.buildingscience.
com/documents/digests/bsd-105
understanding-drainage-planes/files/
bsd-105_understanding_drainage_
planes.pd), provides a variety o
window installation solutions or
dierent wall types.
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(Top) The Building America Clark
Residence retrofit case study demonstrates
the use o high-quality storm windows
(www.buildingscience.com) a solution to
improving window e ciency.
(Bottom) An Insulated Glass Unit (IGU) is
installed as a storm window over stained
glass. Photo by Bruce Kinzey
There is a need to demon
strate there are ways to beenergy efficient without
replacing windows, and that
historic buildings oten have natural
advantages to ventilate, heat, and
cool, said Rock Island Preservation
Commission Chairman Robert Braun.
home, and/or are part o the historic character o the house should
not be removed but maintained in good operating condition. I the
original design included these eatures but they are no longer part o
the structure, consider replacing them in a manner consistent with
the Secretarys Standards or the treatment o historic properties
and guidelines or preserving, rehabilitating, restoring, and
reconstructing historic houses.
Massachusetts 1760 Cape
The Clark Residence retroft (www.buildingscience.com/documents/
case-studies/cs-ma-ngrid-deep-energy-retroft?topic=resources/
retrofts) demonstrates how a Cape Cod home, circa 1760, can be
energy efcient and retain a good deal o its historic character.
The original windows had been replaced with relatively new
wood-rame windows, but they did not oer sufcient thermal
perormance and the homeowners were disinclined to replace
them. Building Science Corporation, a Building America team,determined that adding high quality exterior storm windows
oered the best combination o improved thermal perormance,
interior condensation control, and exterior rain shielding or
the windows. The resulting window specifcations included new
storm windows over existing wood-ramed, double-glazed, low-E
windows. When considering the house as a system, in this case
there was concern that air-impermeable and vapor-retarding
insulation, would put the structure at risk because it could no
longer dry to the inside. To avoid this problem, the renovators
installed new ashing and made other corrections to the water
drainage plane to keep the water away rom the structure.
The Color of Glass
An issue to consider when adding storm windows or replacing
windows is the color o the glass. Glass color will inuence the
quality o light within a building and can also contrast with
other glass already present or being added to the building. Oten,
operable windows like casements and sliders are replaced and
storm windows are added to fxed windows. The storm and the
replacement windows may incorporate glass rom dierent sources
and appear dierent i compared side-by-side. The same type o
comparison may be true when replacement or storm windows
are installed near windows that are let as-is. Perhaps more
importantly, tinted glass may obscure existing window eatures.
Discuss this issue with the window supplier to ensure the selection
o consistent glass color, and glass that does not obscure original
window eatures.
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Systems for Heating and Cooling a House
Pasadena Ranch House
The comprehensive energy audit on the Building America Hartman
Baldwin Design/Build, Pasadena, Caliornia retroft (Pasadena;
http://www1.eere.energy.gov/buildings/building_america/hot_dry_mixed_case_studies.html) provided direction beore the team began
sealing the building shell and installing a new HVAC system. The
homeowner was surprised to learn that the bottom o the return
plenum had rusted out and was open to the crawlspace oor.
Not all audits will point to such clear problems, but they will
provide the inormation to address the heating and cooling system
needs. Depending upon the age o the home, it may have a heating
and cooling system that is very dierent rom most contemporary
homesone that may have relied heavily on passive heating or
cooling, such as shading and cross ventilation rom open windows.Beore installing a new system, ensure that these passive historic
heating and cooling eatures have been maximized. Also ensure that
the recommended energy retroftting derived rom the energy audit
has been completed.
I the home has open chases, oor vents, or built-in chimneys
to provide air ow and ventilation, make sure they are currently
being used as efciently as possible. Retain the associated grilles or
other fnishing eatures or their historical character. Even unused
radiators may contribute to the historic character o the house, so
consider retaining them.
Ceiling ans help with both cooling and heating. Window ans can
exhaust hot air or bring cool air in overnight. Whole-house ans,
installed over stairway halls or elsewhere, exhaust hot air that rises
through the house, while pulling in resh air rom the ground level
where it is coolest. Ordinary room ans can make a remarkable
dierence in the summer, and the dierence in terms o energy use
can be signifcant.
In homes with existing central heating and cooling systems,
sealing or repairing the existing duct system may reap signifcantbenefts. As noted in the Building America Best Practices Guide,
Air Sealing: A Guide or Contractors to Share with Homeowners,
all ducts should be sealed, especially in attics, vented crawlspaces,
and rim areas. In older homes, wall cavities and oor joist cavities
are sometimes used as return ducts to bring air rom the return
registers back to the air-handler unit, but these building cavities are
The Building America Pasadena Ranch
House case study demonstrates the
value o beginning with an energy
audit. Illustrated here is an open plenum
discovered in the crawlspace (www.eere.
energy.gov/buildings/building_america/
hot_dry_mixed_case_studies.html).
All ducts should be sealed,
especially in attics, vented crawlspaces,
and rim areas. For more inormation,
see Building Americas Air Sealing:
A Guide or Contractors to Sharewith Homeowners (http://apps1.eere.
energy.gov/buildings/publications/
pds/building_america/ba_airsealing_
report.pd).
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This historic home uses Unicos Small Duct
High Velocity HVAC equipment, to heat
and cool the home without modifications
to the original historic structure.
Photo by Unico
rarely air sealed and should be replaced with sealed ducts. Reer
to the aorementioned Building America Best Practices Guide or
specifc guidance on repairing and sealing existing systems (http://
apps1.eere.energy.gov/buildings/publications/pds/building_america/
ba_airsealing_report.pd).
Briey, three situations a renovator may ace when replacing a
system include the need to replace the duct system, replace electric
resistance or steam heating, or add air cooling. The limitations o
replacing existing systems, based in part on U.S. Department o
Energy Energy Efciency and Renewable Energy, Energy Savers:
Limitations When Replacing Existing Heating Systems (www.
energysavers.gov/your_home/space_heating_cooling/index.cm/
mytopic=12320), are highlighted below:
INSTALLING NEW DUCT SYSTEMS. When intending to install
new duct systems in a historic house, plan the air delivery system
careully. It should be efcient without changing the homes
historic character by introducing unsightly transoms, dropped
ceilings, etc. While new homes should always have their urnaces
and air handlers located in a conditioned space, this is not always
possible in historic houses. However, i the attic and/or basement/
crawlspace have been converted to conditioned space these spaces
will generally be the best locations or the equipment and ducts.
In some multi-story homes, however, a dierent option will be
needed. High-velocity mini-ducts may provide a solution, because
they orce air through plastic eeder ducts that are only 2 inches
in diameter. These ducts can be easily threaded through cavities in
walls, oors, and ceilings.
A downside o installing mini-ducts is that they generally require
more outlets (2-inch-diameter round ducts): roughly fve outlets
per ton o cooling, or one outlet or every 2400 Btu o heating.
These outlets will likely result in higher costs to install the system.
When installing mini ducts, keep in mind the appearance o the
house during preliminary planning. Outlets can stand out in a
room and their placement is very important, especially when
preserving or restoring a home. Consider putting the outlets in the
corners o oors and ceilings.
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ENERGY PERFORMANCE TECHNIQUES AND TECHNOLOGIES PRESERVING HISTORIC HOMES
REPLACING ELECTRIC RESISTANCE OR STEAM HEATING
WITH HOT-WATER BASEBOARD HEATING. In homes
without ducts, replacing electric resistance baseboard heaters or
steam systems with a hot-water baseboard system can avoid the
need or new ducts, and may limit the overall cost. Replacing an
electric resistance system usually will require extensive plumbing,
but installing it may be less problematic than installing new ducts.
Converting steam systems to hot water is generally only easible in
two-pipe steam systems.
ADDING AIR COOLING TO A HEATED FORCED-AIR
(DUCT) SYSTEM AND INSTALLING DUCTS. This can be
accomplished by adding central air to a orced-air system or
switching to a heat pump. System sizing should not be done beore
the energy audit has been carried out and all weatherization has
been completed. While heat pumps typically require larger duct
systems, duct systems in existing homes are oten unnecessarily
large and rather than being energy efcient, end up wasting energy
and money. Once the home has been made more efcient the sizing
may be appropriate.
Massachusetts Mid-19th Century Farmhouse
In the case o the Bedord Farmhouse, the retroft accomplished
its goals by insulating the attic and basement to create conditioned
spaces. The gas urnace was installed in the newly conditioned space,
and the air handler and distribution system were located entirely
within conditioned space, using sheet metal trunks and run-outs and
ducted returns rom the upstairs bedrooms.
Florida Victorian
The Williams home project aced a dierent challenge to maximize
the original design o passive cooling. Because the home was to
be used as a museum with fxed hours throughout the summer
months, the decision was made to provide cooling. First, the natural
system was optimized, reducing the amount o humidity and dry
air loss through air sealing, insulation, and shading/reectivity. The
builder used the high-velocity mini-duct distribution system, citing
two advantages in its situationbecause the outlets are smaller,
they are less noticeable, and the delivered air temperature is colderthan conventional systems, which improves the dehumidifcation
properties o the cooled air. Dehumidifcation was importantas
the builder energy-retroft the home and added air conditioning it
changed the system, aecting the way temperatures and humidity
moved through the building and building envelope.
Building Americas BedfordFarmhouse High-Performance
Retrofit Prototype accomplished
its retrofitting goals by locating the gas
urnace in the conditioned attic and
locating the air-handler and distribution
systems within conditioned space(or more inormation, see
www.buildingscience.com/documents/
case-studies/cold-climate-bedord
armhouse-retrofit-case-study).
The Williams home project
Cooling Load Reduction and Air
Conditioner Design in a 19th Century
Florida House Museumoptimized the
homes natural system and installed a
high-velocity, mini-duct distribution
system (or more inormation, see
www.sec.uc.edu/en/publications/pd/
FSEC-CR-1508-05.pd).
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When retrofitting with can lights, make
sure they are insulation-contact air tight
(ICAT) and labeled as meeting ASTM E283
when tested at 1.57 ps (75 Pa) pressure
diferential with no more than 2.0 cm o
air movement and sealed with a gasket
or caulk between the housing and interior
wall or ceiling covering.
Lighting Options
Incandescent lighting has traditionallydelivered about 85% o household illumina
tion. Incandescent lamps operate without a
ballast, are dimmable and instantly control
lable, and light up instantly. Most amiliar are
the standard pear-shaped, screw-in A-type
incandescent light bulbs. They produce a
warm light and provide excellent color qual
ity. They have a low ecacy compared to all
other lighting options (10 to 17 lumens per
watt) and a short average operating lie (750
to 2500 hours).
Fluorescent lamps use 25% to 35% o
the energy used by incandescent lamps
to provide the same amount o illumination (ecacy o 100 lumens per watt)
and last about 10 times longer (7,000 to
24,000 hours). Improvements in technol
ogy have resulted in fluorescent lamps with
color temperature and color rendition that
are comparable to incandescent lamps.
LED lights use 35% to 50% o the energy
used by an incandescent lamp to provide
the same amount o illumination (luminaire
ecacy o about 70 lumens per watt) and
last longer than incandescent or fluorescent
bulbs. (Good-quality white LEDs in well-
designed fixtures are expected to have auseul lie o 30,000 to 50,000 hours.) LED
device ecacy doesnt tell the whole story.
Good LED system and luminaire design is
imperative to energy-e cient LED lighting
fixtures. For example, a replacement LED
downlight combines thermal management
and optical design to produce up to 700
lumens using only 6 to 7 watts.
Citation: rom LED Basics: What retailers, energy e ciencyadvocates, and consumers need to know to make inormed
buying decisions (2 pages, November 2009; www.eere.
energy.gov/buildings/ssl/actsheets.html).
Lighting
Artifcial lighting consumes almost 15% o household electricity,
and signifcant energy savings can be achieved by retroftting a
homes lighting. Note that older homes started out with no lighting
or gas lighting and have already been modifed at least once. Useo new lighting technologies can reduce lighting energy use in
homes by 50% to 75%. Advances in lighting controls oer urther
energy savings by reducing the amount o time lights are on but
not serving a useul purpose. Advanced lighting controls also oer
a new amenitylights that come on automatically when they are
needed (http://apps1.eere.energy.gov/buildings/publications/pds/
building_america/26467.pd).
Unlike other energy-retroftting techniques, lighting changes have
ewer impacts on other house systems; the biggest impact is on
reducing the cooling load in summer. New compact uorescentlamps can be ound or many socket styles and sizes. Their use will
reduce the heating load and the energy budget o the home. Consider
installing and using task lighting and LED applications that will
enhance the eel o the room. LEDs are particularly appropriate
or downlighting, under-cabinet lighting, and specifc task lighting.
Furthermore, use o a wide range o sensor light fxtures on the
market, i used properly, will help to conserve energy.
Existing light fxtures are an important element o a historic house
whether or not they are unctional. For example, unused gas light
fxtures can be retained as historic elements o decor.
Finally, careul trimming o exterior landscaping elements that
detract rom the natural interior lighting also should be considered
to improve lighting in the home.
Solid-State Lighting Research:
Solid-state lighting technologies are changing and improving rapidly, and
products arriving on the market exhibit a wide range o perormance.
The DOE Commercially Available LED Product Evaluation and Reporting
(CALiPER) program provides reliable unbiased product perormance
inormation (www.eere.energy.gov/buildings/ssl/caliper.html).
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Other Considerations During an Energy Retrofit
Several retroftting options wont necessarily be the ocus o the
energy audit, but they should be considered in an energy retroft,
e.g., porches, landscaping, and seismic retrofts
Porches
Porches should not be ignored when considering ways to make
a home more energy efcient; efciencies can be gained rom
insulating and air sealing points where porch roos intersect house
walls. Beore adding insulation, make sure the drainage plane is not
allowing water to run between the porch and house, or within the
porch roo structure.
There are also simple ways o making a porch a more temperate and
attractive place to spend time. For example, installing an awning orplanting shade trees can transorm the space. Adding a ceiling can
keep the heat rom bearing down on occupants. Installing a ceiling
an can ensure air movement, without detracting rom the general
eel and historical quality o the porch.
Originally designed or shade and shelter rom the elements and
outdoor living area, porches are sometimes walled in and fnished to
provide additional interior space. Doing this may detract rom the
ow o spaces within the home and change its historic character. I
additional interior space is needed, consider adding it where it will
have less o an impact on the historic image that the home presentsto the street. I a glassed-in ront porch already exists, consider
returning it to its original confguration. This will enhance the
historic character o the house while providing an attractive, shaded
outdoor space.
Landscaping and Siting
I the property landscaping has been maintained over the lie o
the home, it will likely include trees and other eatures that are
aesthetically compatible with the home and provide shade and wind
breaks. Historic landscape eatures may also include valuable oreven irreplaceable plant material, such as mature trees and owering
shrubs that would take many decades to replicate. Beore removing
historic plantings, consider that they are there or a reason and they
are part o the homes historic character.
The Building America Tucson Adobe case
study retained the historic landscaping
with plants and ground cover that require
minimum irrigation (www.eere.energy.
gov/buildings/building_america/hot_dry_
mixed_case_studies.html).
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