BUILDING ENERGY - Fall 2017 - 42

FEATURE: TRANSPARENT INSULATION MATERIALS

SAF - A SOLAR
FA ADE TO STAY?
®

BY ERIC NELSON

PEER REVIEWED BY
JENNA IDE

INTRODUCTION
Since the 60s, many innovative building strategies
have been developed that deviate from traditional
building practices by incorporating ambient energy
sources, especially solar, into the building (skin) for
passive heating or cooling, producing warm water or
natural daylighting. Examples are the trombe wall
or the transparent insulation materials (TIMs), some
of which are still in use today in one form or another.
However, few concepts have really been able to take
hold in conventional building practices. Reasons for
that are numerous, and might include cost, energy
prices, problems of overheating, durability, life
expectancy, maintenance or simply architectural
appeal. Most often such systems are add-ons,
meaning that they do not entirely replace an existing
technology or standard building component (i.e.,
the cladding, the window or the wall). Breaking from
traditional building methods seems to be extremely
difficult not only physically, but also psychologically.
Giuseppe Fent, a Swiss architect has extensively
studied these systems, especially the concept of
transparent insulation materials (TIMs). TIMs absorb
solar energy and convert it into heat, which is then
transmitted through conduction and radiation, while
the typical heat loss through convection is greatly
suppressed. However, because these systems have
too many drawbacks and can be architecturally
challenging to implement, Fent decided to develop
his own system that would be highly energy efficient
and low-tech, using only eco-friendly materials.

FIGURE 1: CLOSE-UP OF THE SAF® SYSTEM.
PHOTO CREDIT: NELSON ARCHITECH GMBH.

42 * BUILDINGENERGY VOL. 36 NO. 2 | FALL 2017

Furthermore, the system was not allowed to
be perceived as an add-on, but needed to be an
integral part of the building envelope construction
and design.
By 1999 he built his first three single family
houses with his own invention, a high performance
cladding system called Lucido® (in Europe only). In
subsequent years the system has evolved and found
its way into numerous multi-residential, commercial
and institutional buildings, both in new construction
and deep energy retrofits. A separate, independent
company is now marketing and selling this system In
North America under the name SAF®.
SAF®
Conventional insulation systems decouple the
building's interior and exterior climate conditions
to the impossible end of creating an airtight,
energy-tight barrier between the two. As an antidote
to this, SAF® incorporates the outdoor energy sources
into the exterior skin, creating a thermal sun-warmed
buffer that heats up over the course of the daylight
hours (Figure 1). After sunset, the wood absorber
cools over the next 5 to 9 hours (Figure 2). This cooling
period gives the building a thermal buffer against the
cold exterior temperatures to which it is exposed. This
cycle dramatically reduces the building's heat loss. In
summer, when the solar incident angle is higher than
in winter, a reverse process takes place: the uniquely
angled wood slats of the solid wood heat-absorber
shade the fa ade from direct solar impact while the

FIGURE 2: TYPICAL WALL SECTION WITH SAF®. THE SAF®
SYSTEM WITH A WOOD ABSORBER, AN AIR GAP AND A
PROTECTIVE GLASS COVER MOUNTED ON A MINIMALLY
INSULATED STRUCTURAL WALL.
GRAPHIC BY NELSON ARCHITECH GMBH.



BUILDING ENERGY - Fall 2017

Table of Contents for the Digital Edition of BUILDING ENERGY - Fall 2017

From the Executive Director: A strategic plan for emerging professionals.
From the Board Chair: Taking flight into new territory.
What is Strategic Electrification? Simply Put, It’s an Energy Transformation: A core pathway to deep carbon reduction.
Better Steam Heat: Generating steam system upgrades in New York City.
Going All the Way:What it will really take to achieve net zero energy in Burlington, VT.
Are You Forging the Weakest Link?: A deeper dive into how the quest for resilience alters the design process.
Air Quality in Your Bedroom: Nighttime Carbon Dioxide Levels in the Bedrooms of 22 Vermont Homes: Can occupants of leaky houses breathe easy in their sleep?
Inclusive Diversity Key to Sustainability: Opinion: Sustainability planning must embrace diversity.
BuildingEnergy Bottom Lines: An interview with Jonathan Orpin.
High Performance Walls: Discover an alternative to traditional insulation methods that can reach superior insulation performance with thinner walls.
SAF®– A Solar Faade to Stay?: A technical overview of the newest attachment systems in the low-energy construction market.
NESEA Green Pages: This premier resource for sustainability professionals in the Northeast and beyond is just a few pages away. To have your business listed in next year’s Green Pages and become a NESEA business member today, visit nesea.org/join.
Index to Advertisers
BUILDING ENERGY - Fall 2017 - Intro
BUILDING ENERGY - Fall 2017 - cover1
BUILDING ENERGY - Fall 2017 - cover2
BUILDING ENERGY - Fall 2017 - 3
BUILDING ENERGY - Fall 2017 - 4
BUILDING ENERGY - Fall 2017 - 5
BUILDING ENERGY - Fall 2017 - From the Executive Director: A strategic plan for emerging professionals.
BUILDING ENERGY - Fall 2017 - 7
BUILDING ENERGY - Fall 2017 - From the Board Chair: Taking flight into new territory.
BUILDING ENERGY - Fall 2017 - 9
BUILDING ENERGY - Fall 2017 - What is Strategic Electrification? Simply Put, It’s an Energy Transformation: A core pathway to deep carbon reduction.
BUILDING ENERGY - Fall 2017 - 11
BUILDING ENERGY - Fall 2017 - 12
BUILDING ENERGY - Fall 2017 - 13
BUILDING ENERGY - Fall 2017 - 14
BUILDING ENERGY - Fall 2017 - 15
BUILDING ENERGY - Fall 2017 - Better Steam Heat: Generating steam system upgrades in New York City.
BUILDING ENERGY - Fall 2017 - 17
BUILDING ENERGY - Fall 2017 - 18
BUILDING ENERGY - Fall 2017 - 19
BUILDING ENERGY - Fall 2017 - INSERT1
BUILDING ENERGY - Fall 2017 - INSERT2
BUILDING ENERGY - Fall 2017 - Going All the Way:What it will really take to achieve net zero energy in Burlington, VT.
BUILDING ENERGY - Fall 2017 - 21
BUILDING ENERGY - Fall 2017 - 22
BUILDING ENERGY - Fall 2017 - 23
BUILDING ENERGY - Fall 2017 - Are You Forging the Weakest Link?: A deeper dive into how the quest for resilience alters the design process.
BUILDING ENERGY - Fall 2017 - 25
BUILDING ENERGY - Fall 2017 - 26
BUILDING ENERGY - Fall 2017 - 27
BUILDING ENERGY - Fall 2017 - 28
BUILDING ENERGY - Fall 2017 - 29
BUILDING ENERGY - Fall 2017 - Air Quality in Your Bedroom: Nighttime Carbon Dioxide Levels in the Bedrooms of 22 Vermont Homes: Can occupants of leaky houses breathe easy in their sleep?
BUILDING ENERGY - Fall 2017 - 31
BUILDING ENERGY - Fall 2017 - 32
BUILDING ENERGY - Fall 2017 - 33
BUILDING ENERGY - Fall 2017 - Inclusive Diversity Key to Sustainability: Opinion: Sustainability planning must embrace diversity.
BUILDING ENERGY - Fall 2017 - 35
BUILDING ENERGY - Fall 2017 - BuildingEnergy Bottom Lines: An interview with Jonathan Orpin.
BUILDING ENERGY - Fall 2017 - 37
BUILDING ENERGY - Fall 2017 - High Performance Walls: Discover an alternative to traditional insulation methods that can reach superior insulation performance with thinner walls.
BUILDING ENERGY - Fall 2017 - 39
BUILDING ENERGY - Fall 2017 - 40
BUILDING ENERGY - Fall 2017 - 41
BUILDING ENERGY - Fall 2017 - SAF®– A Solar Faade to Stay?: A technical overview of the newest attachment systems in the low-energy construction market.
BUILDING ENERGY - Fall 2017 - 43
BUILDING ENERGY - Fall 2017 - 44
BUILDING ENERGY - Fall 2017 - 45
BUILDING ENERGY - Fall 2017 - 46
BUILDING ENERGY - Fall 2017 - 47
BUILDING ENERGY - Fall 2017 - NESEA Green Pages: This premier resource for sustainability professionals in the Northeast and beyond is just a few pages away. To have your business listed in next year’s Green Pages and become a NESEA business member today, visit nesea.org/join.
BUILDING ENERGY - Fall 2017 - 49
BUILDING ENERGY - Fall 2017 - 50
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BUILDING ENERGY - Fall 2017 - INSERT4
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BUILDING ENERGY - Fall 2017 - 75
BUILDING ENERGY - Fall 2017 - 76
BUILDING ENERGY - Fall 2017 - Index to Advertisers
BUILDING ENERGY - Fall 2017 - 78
BUILDING ENERGY - Fall 2017 - cover3
BUILDING ENERGY - Fall 2017 - cover4
BUILDING ENERGY - Fall 2017 - outsert1
BUILDING ENERGY - Fall 2017 - outsert2
BUILDING ENERGY - Fall 2017 - outsert3
BUILDING ENERGY - Fall 2017 - outsert4
BUILDING ENERGY - Fall 2017 - outsert5
BUILDING ENERGY - Fall 2017 - outsert6
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