Tag Archives: APTNW

Analysis: Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

DOCOMOMO_OREGON and the Northwest Chapter of the Association for Preservation Technology recently held an Energy Conservation Symposium that explored issues facing mid-century modern buildings: How can modern historic buildings comply with today’s energy conservation standards? Is it possible to maintain the integrity of the historic building materials and aesthetics while also meeting new energy conservation requirements?

At PMA we believe that while challenging, it is possible to maintain the integrity of these historic mid-century modern buildings and meet new energy conservation requirements. In an effort to explore this possibility, we submitted an abstract for the symposium, and Halla Hoffer, AIA, subsequently presented on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures.
on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures


BACKGROUND
Effective daylighting can reduce both lighting and cooling loads while improving user comfort, satisfaction, and health. Despite plentiful glass, using daylight in mid-century modern building can be challenging. Glare and uneven light distribution can cause user discomfort and pose challenges to effectively daylighting spaces. Frequently, artificial lighting is used to balance lighting in spaces over lit by the sun, negating any potential energy savings. For existing buildings, the available methods to provide effective daylighting are limited by the existing constructions and configuration. To both preserve existing structures and provide ample daylight a critical question must be answered – what are the best practices for improving daylight in existing buildings? This study provides insight to daylighting existing structures, specifically, how light can be controlled and distributed in mid-century modern buildings with plentiful glazing.

1963 RESIDENTIAL TOWER
This study explores and analyzes how common daylighting strategies can be implemented on existing mid-century modern structures. The study focuses on a sixteen-story 1963 residential tower in Portland, Oregon, and explores how interior reflectivity, interior/exterior light shelves, shading, and glazing can impact daylight availability and distribution. The study looks at a variety of ways each strategy can be implemented and analyzes the results to determine best practices based on daylight distribution/availability, glare, lighting loads, and heating/cooling loads.
on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

TOOLS USED FOR SPECIFIC ANALYSIS
Emerging tools and technologies provide effective methods of analyzing hundreds of different daylighting simulations. Applications such as Grasshopper and Dynamo, which are visual programming environments for Rhinoceros 3D and Revit respectively, allow users to explore a variety of different design interventions and determine optimal solutions. Prior to starting the daylight analysis, we began with a “base geometry” of the existing conditions that we modeled in Rhinoceros 3D. We then developed a Grasshopper file to create daylighting interventions. For this study the interventions consisted of interior light shelves and exterior shading devices based on numerical inputs for shelf depth and height. Using Grasshopper in lieu of traditional 3D modeling allowed us to systematically test multiple variations of intervention geometry. In addition to studying how new geometries would impact daylighting we also studied how existing/new materials could impact daylighting performance.
on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

The daylighting analysis was performed using DIVA for Rhino, a plug-in that performs daylighting and energy analysis directly in Rhino. DIVA also offers several Grasshopper nodes, allowing the analysis to be controlled and managed directly in Grasshopper. For this analysis the primary results we extracted and used to measure performance included:

  • Annual Daylight: Percentage of time space receives at least 300 lux. This value can be mapped over the area under analysis. Typically, areas that receive 300 lux at least 50% of the time have the potential for daylighting.
  • Spatial Daylight Autonomy (sDA): Percentage of a space that receives 300 lux for at least 50% of the annual occupied hours. This metric provides a single number for quickly determining daylight potential. A value over 55 indicates that daylighting will be at a minimum nominally accepted by occupants. A value over 75 denotes a space where daylighting will likely be preferred by occupants.
  • Annual Sunlight Exposure (ASE): Percentage of a space that receives over 1,000 lux for at least 250 hours per year. High values indicate that the space may be overlit and cause glare/discomfort.
  • Daylight Factor: A ratio comparing light levels on the interior of the structure to the light levels on the exterior. Typically, a value under 2% indicates that the space cannot be adequately daylit, a value between 2%-5% is preferred for daylighting, and a value over 5% indicates that the space is well daylight, but may be overlit.

    • on Best Practices for Providing Effective Daylight in Mid-Century Modern Structures

    CONCLUSIONS
    Reflective interior surfaces can have a significant impact on daylight distribution.

    Without any shading there is a high probability for glare according to ASE and DF values.

    Interior light shelves alone can reduce the ASE values and the probability of glare.

    Interior light shelves alone are not as effective as exterior shading devices in reducing glare.

    A combination of reflective interior materials, interior light shelves, and exterior shading devices is the most effective method to provide adequate levels and even distribution of light.


    Written and presented by Halla Hoffer, AIA, Assoc. DBIA / Associate

    Long Term Impacts of Masonry Waterproofing Sealers

    Product X works as a masonry sealer, but what are the long-term ramifications of using Product X on masonry buildings? Masonry sealers come in a wide variety of formulations, but how do the various chemical compositions react to environmental conditions and what affect does the formulation have on the masonry? Most masonry waterproofing sealers specified by architects and conservators, installed by contractors, and requested by property owners are based on Silicone (═Si═ ) chemistry. There are three popular groups of silicone based materials being used as waterproofing materials: 1) silicates, 2) the group of silane, siloxane, siliconate; and 3) silicones. Silicates, similar to Product X, provide waterproofing properties by filling the pore structure of building materials with silicon dioxide (SiO2) precipitation. Common silicates are sand, Portland cement, and other natural occurring minerals. Silanes, siloxanes and siliconates provide waterproofing properties by bonding with the substrate. They are often referred to as penetrating sealers. Silicones do not form chemical bonds with the substrate. Silicones provide waterproofing properties by forming a non-bonded film. Such products are labeled as thin-film sealers.
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    SILICATES
    Silicates are most commonly used in crystalline type water proofing agents for concrete. Their use is generally focused on concrete substrates. However, it is known that strongly alkaline, aqueous solutions of methyl silicates can be used to impregnate masonry. Such solutions often depend upon caustic soda for their alkalinity. Impregnation of masonry with such solutions is often disadvantageous, however, particularly due to the high alkalinity. For example, the high caustic soda content of the solution will cause a gradual removal of the organosilicon compounds from the interstices of the masonry by chemical combination with the surfaces of the masonry surrounding the interstitial voids. Moreover, the caustic soda solution reacts with carbon dioxide or other acidic components of the air which gives rise to salting out and the formation of efflorescence on the masonry. (1)

    SILANE, SILOXANE, SILCONATES
    Silane, siloxane, silconates are penetrating type of sealants. Their effectiveness is dependend on the porosity of the substrate and the dosage of repellant applied. Each manufacturer will have unique requirements for the application and dwell time of their sealer. Silanes and siloxanes form a chemical bond with siliceous containing materials. Silanes and siloxanes go through three reactions when applied to a masonry surface: hydroloysis, condensation, and bonding. During the condensation phase, the moisture vapor transmission rate is critical to preventing moisture accumulation behind the sealer layer.

    With penetration type sealers, it is critical to the longevity of substrate (masonry) that the moisture vapor transmission of the sealer is actually known. There has been very little third party testing of vapor transmission and each product manufacturer provides varying ways of testing transmission. In addition, the active ingredient content of the sealer formulation and the coverage rate will greatly affect the moisture vapor transmission. In other words, performance in the field will vary greatly from highly controlled laboratory testing.

    Siliconates are water soluble and they impart water repellency on porous surfaces. A drawback to using diluted siliconate solution for waterproofing applications is that siliconates react with carbon dioxide and carbonatious matters present in the substrate to form a water repellent, water-insoluble, white colored precipitate. This white layer may become quite visible and require aggressive removal procedures resulting in objectionable appearance or scarification of the surface during removal processes.

    SILICONE
    The effectiveness of silicone sealer depends on the alkyl group used (which directly influences its resistance to alkaline conditions), the amount of exposure to ultraviolet light and the level of moisture in the masonry when the silicone is applied. (2)

    The proliferation of masonry coatings on the market, and the continued pervasive use of the coatings, requires the architect, engineer, contractor, and conservator become more knowledgeable on the wide variety of coating formulations, the continued evolution of those formulations, and understand both the right application of the product and potential detrimental effects of using the wrong product on historic substrates.

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    CASE STUDY: WASHINGTON STATE UNIVERSITY, DUNCAN DUNN HALL
    In preparation of a major renovation, Peter Meijer Architect, PC was retained in 2010 to conduct a general exterior condition assessment of Duncan Dunn Hall on the campus of Washington State University, Pullman, Washington.

    Duncan Dunn was constructed in 1926 as a women’s dormitory for Washington State University, then named Washington State College. It is located in the heart of the WSU campus, facing north towards Linden Avenue. First known as the “New Dorm,” the building cost $150,000.00 to build at that time, and could house 140 students. The architect, Stanley Smith, was the head of the department of architectural engineering and was also the official University Architect.
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    The predominant material present on Duncan Dunn is a solid brick unit, brownish red in color, and approximately 8” x 3 7/8” x 2 3/8” in size. At the time of assessment the brick had a very prominent unsightly, white coating over 60% of the masonry facades.

    WSU-PMAPDX_masonry_sealers-003Believing the white haze was a result of UV degradation of a masonry sealer, PMA conducted Reunion Internationale des Laboratoires D’essais et de Recherches sur les Materiaux et les Constructions (RILEM) tube tests of water absorption on the exterior brick on Duncan Dunn Hall. The area of brick chosen for the test was out of direct sunlight to avoid affecting the results and was conducted during dry weather. No movement of the water over a 45 minute period was recorded during the test. Masonry units, even those constructed with high quality clays under controlled firing conditions will absorb some water. The results of the field test on Duncan Dunn, along with the white surface haze, reinforced the assumption of the presence of a masonry coating.

    Communication with WSU personnel and their internal research surmised that “the building may have had a sealer put on after the original construction. [WSU cannot verify the application through original records] but do know [that a sealer] was not used on a regular basis after [construction completion.] Back in the 70’s some “miracle sealer” of some sort was introduced on Campus and used at a few locations. Duncan Dunn Hall was among the buildings [receiving masonry sealers.] Today you can see the remnants of this as a white powdery surface that almost looks like efflorescence. [WSU] does not know the name of [the sealer] product.”

    To confirm the presence of the sealer, PMA conducted lab testing via polarized light microscopy (PLM) episcopic microscopy, capillary fusion and Fourier-transform infrared spectroscopy (FTIR) per ASTM D1245 and E1252, respectively. FTIR indicated the material to be Poly(2-hydroxypropyl methacrylate), an initially water-miscible acrylic polymer that in these samples is at present very brittle and sloughs rather easily.Testing confirmed the presence of a “water-miscible acrylic polymer”. Due to chemical breakdown under UV, the chalky coating remaining on Duncan Dunn is no longer soluble in water.Because of the insoluble nature of the white haze, low pressure hot-water cleaning methods would not be successful. PMA recommended the Rotec Vortex cleaning system using a mirco-abrasive mixture of dolomite, water, and air. Ultimately this removal processes was successful with no damage to the masonry surface.

    (1) Patent application for new formulation of sealers. (2) Types of Masonry Water Repellents, GSA web site. Information derived from ProSoCo Inc. product literature.

    Written by Peter Meijer AIA, NCARB / Principal