Case study by Domus

SMUD
HOMES OF THE FUTURE
LA VALENTINA NORTH
CASE STUDY
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La Valentina North is a unique
infill housing development located near the La Valentina Station,
a Sacramento Regional Transit light rail station, in downtown
Sacramento, California. The near-Net Zero project consists of four
three-story townhouse style buildings designed with energy efficiency
and environmental stewardship at the core. La Valentina also aims
to promote pedestrian activity, encourage light rail ridership, and
reduce blight within the area.
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SMUD HOMES OF THE FUTURE LA VALENTINA NORTH CASE STUDY

The La Valentina North site is located in the Alkali Flat
neighborhood, the oldest residential neighborhood in Sacramento,
with several century-old buildings dating as far back as 1853. The
site is surrounded by existing urban uses and old infrastructure. In
the 1950s the area became the focus of redevelopment efforts,
although the area continued to suffer from blight, crime, and high retail
vacancies along the 12 th Street corridor into the heart of downtown.
The three lots that were merged for the site had been vacant for 18
years, and both civic leaders and neighborhood group were eager to
see it developed. The La Valentina project was awarded entitlements
after a robust 18-month community outreach process that included
over 20 public meetings. The project received overwhelming support
from the Planning Commission, Design Review, the Mayor, and City
Council, and is widely endorsed by community stakeholders and the
Sacramento Area Council of Governments. The project contributes to
a shared vision that promotes compact, mixed-use development and
more transportation choices. Not only does La Valentina North serve
to provide much-needed affordable housing for local families, but it
sets a very high standard of sustainable design to ensure continued
affordability with respect to energy costs.
The project’s beneficial features started with locating adjacent to
existing public transit and services to reduce car dependency. Next,
the selected site was a brownfield that required extensive remediation
of pre-existing toxic waste, taking a blighted property and turning it
into a healthy one. Then, the new buildings were constructed to be
highly energy efficient in order to conserve resources, lower operating
costs, and ensure user comfort. Finally, photovoltaic panels were
added to provide clean on-site energy production, also relieving
pressure on the existing electrical grid.
SMUD HOMES OF THE FUTURE LA VALENTINA NORTH CASE STUDY 3

There are a multitude of design strategies, some obvious and
some hidden from view, which contribute to the success of this
project. The project is a compact, multi-family design with shared
infrastructure, an intrinsic foundational principal that preserves land
and makes in-fill urban sites economically viable. The sharing of
parking and drives, utilities and other infrastructure means fewer
natural resources are expended per resident than typical sub-urban
development patterns. Common walls and floors help reduce heat loss
and heat gain through the building envelope, and capture and hold
more of the conditioned air. This reduces the energy and resources
used to construct the project, as well as reducing the on-going costs
of maintenance, fueling and ultimately replacement of key building
systems.
Working with the La Valentina design team, energy efficiencies
specifications were developed by SMUD’s Research and
Development Department in partnership with National Renewable
Energy Laboratory (NREL). Early on in the design process, NREL
provided critical energy analysis assistance utilizing BEopt (Building
Energy Optimization) software, a computer program that helps
determine the optimal building design for energy efficiency based
on California’s Title 24, which sets minimum energy performance
standards for heating cooling, water heating and lighting. Following
input in design specifications that included insulation and HVAC
systems, NREL performed BEopt analyses of the typical La
Valentina townhomes. The end result is a project that is “near” net
zero in energy use and cost for the residents. SMUD’s Near Zero
Energy Buildings (NZEB) program is focused on demonstrating
advanced building construction strategies and techniques to the
local building community, home buying public, and building owners
that incorporate high efficiency and on-site, renewable energy
technologies and result in the construction of net zero energy and net
zero peak buildings. Research is conducted through pilot projects,
such as La Valentina North, with the goal of incorporating advanced
building construction strategies and techniques into new construction
and solar programs.
The project is located near existing public transportation and
services, a proximity that reduces vehicle miles traveled (VMT)
and can even eliminate the need to own or use a car. This saves
gas and money, helps decrease carbon footprint and also allows the
project to provide less on-site parking, thus preserving valuable land
in the central city. This Transit Oriented Design is also close to many
essential goods and services in the adjacent commercial neighborhood
and downtown. Many residents are able to walk to stores, services
and activities on a regular basis. Not only does this help to improve
personal health, it creates opportunities for community building.
The increased pedestrian presence and activity has a very beneficial
economic effect for local businesses and also provides more vigilance
in the neighborhood, discouraging crime.
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SMUD HOMES OF THE FUTURE LA VALENTINA NORTH CASE STUDY

The project incorporates design elements to create a friendlier
and safer streetscape. Entries, balconies and major windows are
oriented toward the street and sidewalk to present a people-friendly
and welcoming face to the project, encouraging socialization. This
orientation also means there will be “eyes on the street” from residents
to discourage bad behavior and respond quickly to problems.
Residents share common entrances and facilities such as the laundry
with the result that there is greater opportunity to meet casually and
become acquainted. This extends as well to the central courtyard
space, which not only provides a controlled circulation area for
parking access, but doubles as a central activity space for kids.
The project uses major design elements to make the buildings more
energy efficient. Strategic placement of components such as trellises,
awnings, balconies, roof overhangs and bay window projections serve
to keep the sun from directly entering east, west and south oriented
windows during the hot summer months. This is a first line of defense
to reduce cooling loads and energy use. In the winter months, when
sun angles are lower, some direct light can enter and help to warm
interior spaces. Parking areas are “tucked under” the buildings where
they are completely shaded from the sun. The intervening courtyard is
also shaded for much of the day by the building massing itself, creating
a cool and protected recreational space for kid’s activities. These
features significantly reduce the “heat island” effect of the sun hitting
the pavement, and cool the ambient air temperature in the summer,
creating a pleasant micro-climate.
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There are a number of energy-saving design features that are
“built-in” to the fabric of the building envelope. The exterior walls
have been super insulated to a value of R-30.9, nearly three times
that of traditional 2x4 wood frame construction. First, the exterior
walls employ 2x6 wood framing with damp cellulose blown insulation.
The damp cellulose is superior to standard fiberglass insulation in its
ability to uniformly fill all cavities and seal around components such
as outlet boxes, wiring, plumbing lines, etc. Over the 2x6 framing is
a ½” layer of oriented strand board and a full house wrap “air barrier”
to seal against air infiltration. Next are a primary layer of 1” rigid
polyisocyanurate insulation and a secondary layer of 1” rigid expanded
polystyrene insulation. These insulation panels not only provide
additional “R” value, but they effectively eliminate the heat loss and
gain associated with “thermal bridging” whereby heat travels through
the wood framing members. Finally, there is a full traditional 3-coat
stucco exterior finish for long term durability and protection. Some
limited elements of advanced framing have also been employed where
possible to increase the percentage of insulation to wood in the overall
wall construction.
All ceilings are insulated with 12” of open-cell spray foam insulation
to achieve a value of R-42, nearly 50% greater than common
practice. In addition, there are well-ventilated attics with “radiant
barrier” roof sheathing which minimizes heat gain in the summer and
heat loss in the winter. Also, a polyethylene “warm-side” vapor barrier
has been installed at the ceiling to help prevent infiltration losses and
prevent humid air from migrating into the attic. All joints at walls,
doors and windows as well as electrical boxes and other penetrations
are fully caulked and sealed to further prevent air infiltration and heat
loss or gain.
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SMUD HOMES OF THE FUTURE LA VALENTINA NORTH CASE STUDY

Another important element in creating the efficient building
envelope is the choice of windows. For this project, vinyl-framed
double-glazed windows with low-emissivity coatings were selected for
their superior thermal performance. The vinyl frames provide excellent
resistance to heat transfer – far better than traditional aluminum and
on par with wood, but at an affordable price for this type of project.
Double glazing is now the norm, but these windows go beyond by
including argon gas filler and Energy Star Suncoat Max “Low-E”
coating. The low-e coating reduces conductive as well as direct solar
heat gain and loss by admitting an optimal amount of visible light
while limiting un-wanted ultra-violet and infrared light. The specified
windows achieve a “U-Factor” of between .28 and .30 (depending
on mode of operability) and a SHGC (solar heat gain coefficient) of
0.19. Not only does this significantly improve energy efficient, but it
prevents premature fading of interior finishes such as carpets, drapes
and furniture upholstery.
The building envelope (ceilings, walls, windows) described above is
critical to insure that the building will use as little energy as possible.
The next step is to insure that the energy that is used is used efficiently.
A number of careful selections were made to insure this. All appliances
such as ranges, dishwashers, refrigerators, etc. are Energy Star Tier
2 rated. Residences all have high efficiency gas-electric heating and
air conditioning systems with full duct insulation and HERS testing
for proper air balance, sealing and air quality. Furnaces have an
AFUE of 95 with a variable speed fan and set-back thermostat. The
air conditioning condensers are 18 SEER and 13+ EER. Ducts are
tested for less than 6% leakage. Water heaters are high efficiency gas
“tankless” on-demand type with EF (energy factor) of .82. Another
great feature of the tankless water heaters is that they operate only
when needed, as opposed to traditional tank water heaters that
continually heat a large quantity of water.
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A third party HERS inspector was hired to insure that energy saving
measures and specifications were met. Testing included Duct
Leakage testing, Building Envelope sealing testing, HVAC Cooling Coil
Airflow & Fan Watt Draw testing, High EER Equipment verification,
Refrigerant Charge verification, Maximum Total Cooling Capacity,
Supply Duct Compliance Credits and Quality Insulation Installation. Six
representative units were selected to perform a Home Energy Rating,
(commonly called HERS II rating).
Light fixtures have also been selected for optimum energy efficiency.
All fixtures on the project are “high-efficacy” type including LED and
energy star fluorescent fixtures. Some areas use occupancy sensors
to automatically turn on or off depending on use. Natural light and
ventilation are also provided by carefully placed windows, often on
two sides of a room for cross-ventilation. While minimizing the need
for artificial light, natural light is full-spectrum and “free” and natural
ventilation greatly improves indoor air quality.
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SMUD HOMES OF THE FUTURE LA VALENTINA NORTH CASE STUDY

This was one of the first HERS II audits done on new multifamily
housing construction under Calfiornia’s HERS II program. The Audit
found that on a scale of zero to 250, (with zero being the best and
250 the worst for energy efficiency), La Valentina North’s score
ranged from 15 to 29 with an average score of 18.8. This impressive
score coupled with the 53% above the project’s 2008 Title 24 energy
standard is showing the path to future energy efficient housing
development.
After all the energy conservation features were incorporated, what
was left was to provide for on-site energy production to off-set the
minimal demand that cannot be avoided. This project met that goal
by installing roof-top-mounted photo-voltaic panels that provide nearly
100% of electrical demand for not only the site lighting and other
common area uses, but also individual tenant use. This is not only an
energy saver but makes a big difference to the monthly bottom line for
affordable housing tenants in a tough economy.
Beyond energy use, the project also seeks to conserve natural
resources through water conservation and air quality features. The
landscape utilizes native, drought-tolerant plantings watered by 100%
drip irrigation. Within the living units, the use of low-flow plumbing
fixtures further conserves water. Generous and well-placed windows
for natural ventilation and the use of low VOC paints and coatings, no
added formaldehyde casework components and eco-friendly floor
coverings will help insure a healthy and sustainable environment for
present and future residents. The project utilizes durable materials
with long life-cycles to reduce the need to replace and repair in future
– conserving resources.
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LESSONS LEARNED
To summarize, the project success was a
function of paying careful attention to a number
of important design decisions and strategies:
GOOD SITE SELECTION
CREATING DENSITY
SHARING INFRASTRUCTURE
EFFECTIVE BUILDING MASSING AND ORIENTATION
SHADING TO REDUCE HEAT GAIN
ENERGY-EFFICIENT BUILDING ENVELOPE
ENERGY-EFFICIENT EQUIPMENT AND LIGHTING
ON SITE POWER GENERATION
WATER CONSERVATION AND AIR QUALITY
www.domusd.com | www.smud.org
DURABLE CONSTRUCTION
For more information, visit the Home of the Future website. Hyperlink below:
https://www.smud.org/en/residential/environment/solarsmart-homes/home-of-the-future.htm
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SMUD HOMES OF THE FUTURE LA VALENTINA NORTH CASE STUDY