Case Study: Challenges of Insulating Existing Masonry Buildings in the Commonwealth


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Adapting and repurposing older buildings for new uses with advancing energy and environmental concerns is challenging and requires specific expertise. Bruner/Cott & Associates presents a methodology for the analysis of building envelope improvements in existing buildings focusing on two buildings in Eastern Massachusetts.

This methodology focuses on each building’s unique material characteristics and an approach that not only addresses the concerns of thermal resistance, condensation and freeze/thaw cycles, but also the architectural implications of energy conservation measures.

The team’s extensive experience rehabilitating historic buildings and as building science practitioners enables them to evaluate methods and make decisions related to the building envelope while providing the best architectural solutions.

This presentation will highlight the approach, the decision making process and the results of various completed and on-the- boards projects including Harvard Blackstone Building and the Dartmouth Class of 1953 Dining. The following topics in particular will be addressed: existing envelope construction and masonry characteristics, weather exposure, freeze/thaw events, saturation and density tests, building program and MEP changes that affect air pressure and RH factors, vapor and moisture permeance, compatibility with architectural enclosures, and recommended monitoring systems.

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  • Case Study: Challenges of Insulating Existing Masonry Buildings in the Commonwealth

    1. 1. Challenges of Insulating Existing Masonry Buildings: An Architectural Approach Based on Technical Knowledge presented by Laurie Soave, AIA, LEED AP Associate, Project Architect Bruner/Cott & Associates, Architects
    2. 2. Presentation Goals • Understanding the Decision Making Process – envelope construction and characteristics – methodologies of investigation – environments interior / exterior – existing materials properties and testing – owner involvement – third party experts – monitoring • Audience experience input
    3. 3. Representative Projects Harvard Blackstone Office RenovationMIT Building E60
    4. 4. Methodology • Step 1: Document Existing Building Statistics 1A: Weather 1- Locate building site and determine exposures 2- Map exposure of driving rain 3- Note building climate zone 4- Note number of freeze/thaw excursions per season (Find this information on website: ) 1B: Interior Environment 1- Document existing building program use (i.e. dining/ offices/performance space, lab, art gallery, etc.) 2- Document existing RH factor based on program use and MEP systems
    5. 5. Methodology • Step 1: Document Existing Building Statistics 1C: Pressure 1- Document the existing air pressure on the building (negative or positive) based on the building use and mechanical systems) 1D: Construction 1- Document existing envelope construction: – Wall Construction and R-Value – Roof Construction and R-Value – Dew point locations – Document % fenestration and U-Value
    6. 6. 1D: Construction (cont.) 2- Document roof construction, R-Value and dew point 3- Document conditions of vulnerable areas with potential of exposure to longer wetting periods: (i.e. beam ends, lintels, brick at window openings, spandrel panels below sills, etc.) Methodology
    7. 7. 1E: Testing of Existing Materials Properties (approach Building Science Consultant) 1- Approach Building Science consultant - Permeance testing of entire wall layering materials ( i.e. paint, mortar, terracotta, bricks: face brick, core brick and interior brick) - Scrit test: Measures the degree of saturation in an existing masonry - Dry Density test - Water uptake tests - Thermograph documentation (infrared imaging) - Simulation Software Methodology
    8. 8. Methodology • Step 2: Document Proposed Envelope Improvement Goals 2A: Goals - Increase thermal resistance of wall assembly - Decrease air leakage of envelope assembly - Contain risk of freeze/thaw cycles - Reduce moisture load on brick façade
    9. 9. 2B: Analysis of Improvements 1- Proposed envelope R-Value (in conjunction with MEP systems) 2- Proposed insulation materials - R-Value/in - Vapor & moisture permeance - Fire Rating - Installation sequence - Architectural enclosure options/implications - Flashing compatibility at openings 3- Calculate dew point location 4- Air barriers 5- Proposed condensation controls 6- Implications for building systems installations 7- Reversibility 8- Toxicity 9- Disposal (recycling) options Methodology • Step 2: Document Proposed Envelope Improvement Goals (cont.)
    10. 10. 1- Thermograph testing during and post construction 2- Remote weather station and site monitoring: temperatures at wall face, wall core, ambient; RH levels. Methodology • Step 3: Performance Monitoring – Post construction (owner buy-in and consultant contracts)
    11. 11. Representative Projects • Harvard Blackstone Office Renovation  Originally Constructed 1890’s  Masonry bearing walls with timber beam & floor structure  Brick masonry 3 wythes  Completed renovation for new offices
    12. 12. Harvard University Operational Services Blackstone Office Renovation, Cambridge, MA Case Study – Vapor Migration and Exterior Wall Insulation • Design Goals – Successfully manage the exterior envelope without creating damage due to increased and prolonged moisture content in the existing brick and mortar – Target R-values for the overall envelope • Concerns – Interior insulation that will not impede vapor passage – Continuous air barrier w/minimal cold bridging – Moisture management at brick – Moisture management at window openings – Comparable installations with empirical assessment and data • Strategies – Proper repointing and masonry repairs and sealing of roof wall joints – Detail an interior insulation approach with continuous thermal break – Advocate quantitative approaches including monitoring of insulated and non- insulated walls at various exposures – Provide operable windows
    13. 13. Existing Conditions Review • Visual Review – Rust Jacked Lintels – Cracks – Spalling • Test interior Finish – Vapor barrier Load bearing masonry walls
    14. 14. Analysis of existing interior paint permeance
    15. 15. Process Architectural Considerations
    16. 16. Exterior Wall - Alternate 1 Faced Batt insulation Pros Provides interior insulation Allows air space No special installation Cons Requires ventilation gaps R-Value far below goal No continuous air barrier Limited run space for systems Not approved Process - Options
    17. 17. Process - Options Exterior Wall - Alternate 2 Rigid Insulation Pros Meets the R12 min. goal Semi Permeable insulation Creates continuous thermal break Allows run space for systems Cons Constructability is difficult / tedious No continuous air barrier Careful treatment at penetrations
    18. 18. Selected option - Icynene Insulation Exterior Wall - Alternate 3 Icynene SPF insulation Pros Meets the R12 min. goal Vapor-permeable insulation Creates continuous thermal break Allows run space for systems Dependable air barrier Constructability Cons Specialized trade Careful treatment at penetrations Requires thicker wall section Process - Options
    19. 19. Process existing interior VB paint sandblast 75% paint 3.5” (SPF open cell)
    20. 20. Results
    21. 21. Post Results Recent site visit to begin investigations into vapor/moisture in wall and insulation material performance Efflourescent noted at interior non-insulated stairwells walls. Saturation at north wall bricks
    22. 22. Representative Projects • Arthur D. Little Building; MIT Building E60  Originally Constructed 1917  Masonry Bearing Wall with concrete floor structure  Brick masonry with interior wythe of clay tile  Under renovation for new office and conference space
    23. 23. Existing Conditions Review • Visual Review – Rust Jacked Lintels – Cracks – Spalling • Tested Brick – Cold Water Absorption, ASTM C67 – Boiling Water Absorption, ASTM C67 – Capillary Uptake, ASTM C67 – Dry Density, ASTM C642 – Critical saturation (Scrit) Frost Dilatometry • Tested Mortar – Chemical Analysis – Aggregate Composition – Type Identification • Test interior Finish – Vapor barrier?
    24. 24. Develop Proposal • Establish Design Conditions • Establish Performance Criteria with HVAC • Design Insulating System – Air Barrier – Vapor Barrier – Insulating Layer – Finish • WUFI Analysis Denotes line of temperature across existing uninsulated masonry
    25. 25. Detail
    26. 26. On-Going Concerns • Structural elements embedded in wall • Steel or Wood vulnerable to water • Channels to the exterior Exposed rebar at concrete lintel Voids within wall at sill SCT cores at header courses
    27. 27. Audience Experience Discussion