How can we improve the performance of mid-century office buildings while preserving our architectural heritage?

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1 How can we improve the performance of mid-century office buildings while preserving our architectural heritage? ew York has thousands of commercial buildings built between 1950 and 1980, representing millions of square feet of real estate. According to the Rockefeller Foundation and Deutsche Bank Climate Change Advisors, improving the energy performance of pre- 1980s buildings could generate up to $1 trillion in savings over 10 years. Greening existing buildings is our city s biggest sustainability challenge. ur proposal for 200 Park Avenue preserves the most iconic element of the existing facade: its precast concrete shell. n the north and south, we add a new unitized curtainwall outboard of the concrete that uses emerging materials to generate energy while dynamically controlling solar heat gain and glare. n the east and west, we bring the new envelope inboard of the concrete to highlight the materiality and plasticity of the existing skin. Mid-century commercial buildings perform badly, and in some ways can never meet current standards for energy and comfort. While recladding these buildings might improve their performance, there is an architectural case for preserving midcentury facades as a part of the city fabric. There is also a strong case for avoiding the environmental impacts of demolition. By preserving and overcladding - instead of demolishing and recladding - our proposal reduces the building s environmental impact by 42% over the next 50 years. We see our approach as a template for making needed improvements to ew York s existing building stock. Performance-based preservation is a progressive approach to preservation that enables us to meet the challenges ahead without jettisoning the past. 1 of 10

2 Urban Context Emergy Comfort Materials & Labor Energy Recycle Renewable Resources Facade overcladding Building peration Economy Site heat sink The Pan Am Building has long been criticized for blocking the visual flow of Park Avenue. Since we cannot erase its bulk, our proposal covers the north and south facades with a skin of reflective glass to dematerialize the building s mass. At the east and west facades, we take the opposite approach: bringing the line of enclosure inboard of the existing precast concrete to highlight the building s materiality and depth. Compared to the existing building, our proposal reduces energy use by 54%, reduces carbon by 56%, and reduces the overall burden on our environment by 42% over the next 50 years. Concrete has a high embodied energy and is one of the least recyclable building materials. Rather than demolish the existing precast facade, we are preserving it and adding a high-performance overcladding. The new curtainwall integrates transparent photovoltaics and a switchable D interlayer into the glazing, generating energy and reducing direct solar gain. The dynamic glazing regulates occupant comfort by reducing glare without penalties for daylight penetration. Compared to the existing building, our proposal reduces glare by 91%. 2 of 10

3 Design Proposal WT-01: Tower orth and South Facade Aluminum and glass curtainwall system with decorative stainless steel cladding and shadowboxes anchored outboard of existing precast concrete facade. Glazing on the south facade includes transparent photovoltaic and switchable liquid crystal interlayers. WT-02: Tower East and West Facade Aluminum and glass window wall system installed inboard of existing precast concrete facade. Includes decorative stainless steel cladding at head, sill and jambs and column covers. 3 of 10

4 WT-01: Tower orth and South Facade CC-01 Existing precast concrete GL-01 Insulating glass with tpv,, and low-e coating MT-01 Stainless steel infill and shadowbox Firestop and smoke seal Anchor bracket welded to existing steel C-channel U-Value Vision Spandrel 1.30 W/m2K 0.93 W/m2K 4 of 10

5 WT-02: Tower East and West Facade GL-02 Insulating glass with low-e coating MT-01 Stainless steel cladding CC-01 Existing precast concrete U-Value Vision Spandrel 1.30 W/m2K 0.20 W/m2K 5 of 10

6 Materials GL-01: South Facade IGU with laminated outer lite; tpv interlayer, interlayers with five switching states, and low-e coating uter lite: 3/8 Low-iron, Heat Strengthened Transparent Photovoltaic (tpv) interlayer.030 PVB interlayer Liquid Crystal () interlayer.030 PVB interlayer 3/8 Low-iron, Heat Strengthened Low-e coating on #4 surface with 30% exterior reflectance Cavity: 1/2 airspace w/ Argon fill and warm-edge spacer Inner Lite: 3/8 Low-iron, Fully Tempered Glass Technology The IGU on the south facade combines energy generation with dynamic control of solar heat gain and glare. The outer lite includes a transparent photovoltaic interlayer (tpv) that generates energy over the entire surface of the glass without obstructing views. 1 Behind the PV, a liquid crystal interlayer () allows switchable control of the visible light transmittance for occupant comfort and solar control. 2 A low-e coating on the #4 surface provides low backside hemispherical emissivity and the architecturally desired reflectivity. otes: 1. tpv such as emerging products from Ubiquitous Energy 2. switchable glazing, such as emerging products from EMD/Merck 3. Mention of products does not constitute endorsement GL-02: orth, East, and West Facade IGU with low-e coating uter lite: 3/8 Low-iron, Heat Strengthened; Low-e coating on #2 surface with 30% exterior reflectance Cavity: 1/2 airspace w/ Argon fill and warm-edge spacer Inner Lite: 3/8 Low-iron, Fully Tempered Si 2 PVB tpv PVB PVB Si 2 Low-e UV Vis IR IR Light UV Vis IR Energy transfer and conversion at IGU IR Dark MT-01: Stainless Steel Cladding Finish: Linen textured finish CC-01: Existing exposed-aggregate precast concrete tpv + TC H 3 C Dye H 3 C H3 C H3 C Light Dye H H Dark H 3 C H H H 3 C H3 C H3 C TC m hν m M C60 TC τ 1 0 UV Vis IR λ tpv Transparent Photolvoltaic 1 + τ 1 0 UV Vis IR λ Switchable Liquid Crystal 2 τ = 1 0 UV Vis IR λ Combined Transmittance m Por 6 of 10

7 Installation Existing Step 1 Step 2 Step 3 WT-01 Installation Existing: Full-height fixed precast concrete panels alternating with loose precast spandrel panels Step 1: Remove loose spandrel panels; install anchor assembly to existing steel spandrel beam Step 2: Install curtainwall units from exterior Step 3: Install firestopping, smoke seal and trim from interior 7 of 10

8 Emergy Emergy Emergy Analysis Analysis Emergy of Materials and Energy Environmental Cost (Sej/yr/m2) 1.20E E+16 Emergy (spelled with an m ) is a concept by H.T. dum that allows for evaluation of the stress placed recladding on our (+1%) recladding In terms (+1%) of energy performance, compared to the existing building, our proposed facade 1.00E E+16 keep existing (baseline) keep existing (baseline) environment due to a particular process(es). It is a comprehensive method to evaluate the sustainablity of a building reduces energy use by 54%, reduces carbon by 56%, and generates energy through the use of photovoltaics. 8.00E E+15 proposal. Here, we use emergy to evaluate the environmental cost of keeping existing facade, recladding, 6.00E E+15 overcladding and (-42%) overcladding (-42%) overcladding. Site Energy Use Intensity [M/m 2 ] 4.00E E+15 Environmental Cost (Sej/yr/m2) By 2066, compared to the existing building, the overcladding reduces the cost to the environment by 42%. 0.00E E+00 In contrast, the re-cladding option increases the cost to the environment 2016 by 1% (inital occupancy) 4.00E E (inital (today) occupancy) 2016 (today) 2066 (50 year projection) 2066 (50 year projection) perating Energy, Energy Generation and Carbon Emissions Equipment Heating Cooling Lighting tpv Elec. Gen Keep Existing vs. Re-cladding vs. vercladding Baseline no change to existing facade demolition recycle Proposed verclad Envelope w/ Daylight Controls & Dynamic Glazing -31% -33% environmental cost for the next 50 years = remains constant Emergy Analysis [sej/yr/m2] recladding environmental cost for the next 50 years = increases by 1% perserve structure add high-performance overcladding environmental cost for the next 50 years = decreases by 42% Proposed verclad Envelope w/ Daylight Controls & Dynamic Glazing & Photovoltaics -56% -54% Environmental Cost (Sej/yr/m2) 1.20E E E E E E E (inital occupancy) recladding (+1%) keep existing (baseline) overcladding (-42%) Methodology C 2 Equivalent Annual perational Emissions [M/m 2 ] Carbon Equivalent [tons] Whole building energy models were performed using Energy Plus 8.4 with conceptual level perimeter and core thermal zoning at two representative floors of the Simulations plinth and three and representative Methodology: floors of the tower. All energy models used ideal air loads and included site shading. Envelope and glazing Whole characteristics building energy were models determined were in performed Therm 7.2 using and Window Energy Plus with conceptual level perimeter and core For proposed models with dynamic thermal glazing, zoning at a two Radiance representative 3-phase method floors of was the used plinth to and more three accurately representative determine floors interior of the illuminance tower. All energy distribution and dynamically models switch glazing used ideal properties air loads during and included Energy Plus site shading. runtime. Photovoltaic Envelope and array glazing electricity characteristics generation determined additionally in Therm used (today) (50 year projection) Energy Plus and assumed a % and solar Window t-to-electric 7.2. For efficiency proposed and models does not with account dynamic for glazing, derated a efficiency Radiance 3-phase from cell method temperature was used or inverter to more accurately determine interior illuminance distribution and dynamically switch glazing properties during Energy properties. Plus runtime. Photovoltaic array electricity generation additionally used Energy Plus and assumed a 10% solar t-to-electric efficiency and does not account for derated efficiency from cell temperature or inverter properties. 8 of 10

9 Visual Comfort Annual Glare Analysis (Existing) Glare Control 12am The new glazing dynamically regulates occupant comfort by reducing glare without penalties for daylight penetration. 6am Proposed As compared to the existing design, our proposal reduces glare by 90%, completely eliminating any risk of visual discomfort during the summer months without incurring in additional artificial illumination. The annual glare analysis has been based on the Daylight Glare F M A M Annual Glare Analysis (Proposed) A S D F M A M A S D 12pm 6pm 12am Daylight Glare Probability (DGP) Imperceptible Glare Perceptible Glare Disturbing Glare 1 intolerable Glare Probability index, which takes into account the proximity to the facade, orientation and indirect reflections on fullyfurnished space. Illuminance (lux) Existing of 10

10 Dynamic Glass The dynamic glazing not only improves the interior environment it also registers as a design element on the exterior. The glass changes color as shadows move across the facade over the course of the day. 8:30AM 8:45AM 9:00AM 9:15AM 9:30AM 9:45AM 10:00AM 10 of 10 10:15AM 10:30AM