Retrofitting With a SuperInsulated Metal Panelized Shell Paul Bertram, FCSI, CDT, LEED AP Kingspan 726 Summerhill Dr., Deland, FL 32724 Phone: 386-785-3063 • E-mail: paul.bertram@kingspan.com 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 B e r t r a m • 2 1 1 Abstract The renovation of the 500-unit Castle Square Apartments represents an historic milestone toward reducing the carbon footprint of existing buildings through greater energy efficiency. A portion of the 1960s property, the 192-unit midrise, is the largest deep-energy retrofit ever undertaken in the U.S. Predictive modeling demonstrated energy reduction by 72%, with the envelope representing +30% of the total. One-year-later performance data will be compared to the predictive energy modeling. The difference between the Castle Square project and standard renovations is insulation on the outside of the building with a superinsulated metal panelized shell. Speaker Paul Bertram, FCSI, CDT, LEED AP – Kingspan Paul Bertram is a Fellow of the Construction Specifications Institute (CSI) and a past president of CSI. He has solid expertise in Envelope First Energy Efficiency and Net- Zero Energy strategies, as well as material evaluation and specification. His current work includes energy modeling of building envelopes, energy optimization, and related greenhouse gas (GHG) impacts. Bertram is responsible for coordinating Kingspan’s life cycle assessment development and contributes to its Global Reporting Initiative (GRI) sustainability reporting. He is also part of the strategy team to meet Kingspan’s global mandate of Net Zero Energy for all North American operations. Paul coordinated development of the first-of-its-kind ISO-compliant, UL-certified cradle-to-grave environmental product declaration (EPD) with a “use-phase” benefits study. 2 1 2 • B e r t r a m 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 Challe nges and Opp ort unities in Deep Envel ope Retr ofitti ng The American Council for an Energy- Efficient Economy (ACEEE) published the “International Energy Efficiency Scorecard” in July of 2012, ranking the U.S. ninth out of 12 global economies, and noted that the United States in the last decade has made “limited or little progress toward greater energy efficiency at the national level.” The U.S. Department of Energy’s (DOE’s) “Energy Efficiency & Renewable Energy” (EERE) report notes that more than $400 billion each year is spent to power homes and commercial buildings, consuming more than 70% of all electricity used in the U.S. (about 40% of our nation’s total energy bill) and contributing to almost 40% of the nation’s carbon dioxide emissions. Much of this energy and money (20% or more, on average) is wasted by poorperforming buildings. The 2009 McKinsey Global Energy & Materials study, “Unlocking Energy Efficiency in the U.S. Economy,” reported that one of the top opportunities for improving energy efficiency is retrofitting of existing buildings. The challenge for existing building energy efficiency is to “unlock” that vast potential and realize the benefits of a built environment that is comfortable, efficient, and costeffective. Deep-energy retrofits (DER) that include the building envelope are a challenge because of longer payback and upfront investment. Life cycle costing versus first costs must be projected with return on investment (ROI) and net present value (NPV) for a sound business case. Deep -Energ y Retr ofit The term “deep-energy retrofit” may not be familiar to every building professional, but the concept certainly is: Evaluate poorperforming buildings, execute a number of high-quality renovations of the enclosure and mechanical systems, add renewables where possible, and return energy savings of at least 50% or more to the owners. DER strategies are fairly straightforward. First, improve the enclosure’s insulating value with optimized thermal performance of opaque walls and windows. Then, seal against air leaks, minimizing one of the nation’s leading causes of building energy loss. Once the enclosure is airtight and thermally optimized with energy-efficient windows, the project team can easily rightsize energy conservation measures such as HVAC, lighting, hot water, and building controls. Add renewables such as solar tubes and photovoltaics to further reduce energy consumption for a path to net zero energy. In the past, retrofits of existing buildings typically involved the filling of framed cavity walls with insulation; however, the amount of effective thermal resistance that could be added was limited by the existing stud cavity or strapping depth, the insulation material, and the amount of thermal bridging present in the framing. The addition of insulation to the exterior of existing buildings has been demonstrated to be an effective means to overcome these limitations and provide higher effective R-values for building wall assemblies. The benefits of this approach extend beyond just added thermal resistance. Benefits of increased building durability and air tightness are often realized. By choosing an aggressive approach of envelope-first energy efficiency with a superinsulated exterior envelope, combined with other energy-reduction measures, the residents of Castle Square Apartments, an affordable-housing community in Boston, engaged an integrated design team to cut energy use by 72%. Castle Square Deep Energ y Retr ofit (Der ) Located on Tremont Street in Boston’s South End and constructed in the 1960s, Castle Square Apartments is a 540,000-sq.-ft. mixeduse property composed of 500 affordable apartment units and 20,000 sq. ft. of retail space (Figure 1). In 1987, the Castle Square Tenants’ Organization (CSTO) was established as a nonprofit organization dedicated to preserve Castle Square Apartments as affordable housing for low- and moderate-income residents into perpetuity and to provide comprehensive community and social support. The CSTO engaged a team of professionals, all experts in their respective fields, to Retrofitting With a SuperInsulated Metal Panelized Shell 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 B e r t r a m • 2 1 3 Figure 1 – Brochure image of Castle Square Apartments. retrofit the buildings. Construction started December 10, 2010. The Castle Square/DER-integrated building team included representatives from the CSTO; Winn Development, owner of the project; Building Science Corporation (BSC) as the enclosure specialists; Elton + Hampton Architects, Portsmouth; Petersen Engineering, Inc.; Biome Studio—a zeroenergy and sustainability consulting group; and Pinck and Co., owner’s representative. The team targeted 192 apartments totaling 174,425 sq. ft. for the DER. The team’s challenge was turning a 1960s building made with porous, uninsulated concrete and brick infill walls (R-3) that featured aluminum slider windows and throughwall A/C units into a modern, tightly constructed, energy-efficient multifamily building— without moving tenants out during construction. Castle Square Deep -Energ y Retr ofit Desig n Pri nciples The team, through a series of charrettes that included tenants as well as the design and construction team, established the following six guiding principles for the DER. 1. Superinsulate. A new super-insulated shell, combined with a superinsulated reflective roof, highefficiency windows, and extensive air sealing to increase the insulation value of the building by a factor of 10. 2. Air seal. Air sealing is necessary for optimized thermal performance. Air sealing includes caulking cracks and holes to the outdoors and between apartments. It also limits the stack effect, reduces pests, and improves indoor air. • The super-insulated shell and air sealing is projected to drop heating by 61% and cooling by 68%. 3. Scale down heating and cooling equipment. A superinsulated and air-sealed building requires much less energy to heat and cool. Highefficiency heating equipment will drop the building’s heating needs by 10%. Insulating pipes and use of high-efficiency boilers with indirect hot-water heaters will drop hotwater energy usage by 41%. 4. Improve indoor air quality. Indoor air quality was designed to increase substantially with the use of freshair trickle vents and renovating the existing ventilation system with duct sealing and new air duct dampers. 5. Harness the sun. Solar thermal hot water reduced the building’s energy usage. • H ot-water energy was expected to drop by 37% due to the solar hot-water system. 6. Reduce plug load. Using Energy Star® appliances, fluorescent, and LED lighting fixtures decreased the building’s energy use. • Energy use of refrigerators and lighting is expected to drop by 53%. Through modeling and analysis, the Castle Square Deep-Energy Retrofit project was predicted to reduce the total building energy consumption by 72%. Existi ng Buildi ng Anal ysis The building originally had no wall insulation, with an R-3 wall assembly. After the renovation, the walls were increased to R-40. The roof went from R-20 to R-40. The R-1.3 aluminum-clad slider windows were replaced with R-5 fiberglass casement windows. Extensive energy modeling by BSC, Biome Studio, and the Hickory Consortium estimated the annual energy use for the building with the superinsulated shell and air sealing, new windows, roof retrofit, solar hot-water panels, and new boiler from two separate modeling approaches. Initial energy modeling was calculated by BSC with spreadsheets using the basic calculation: Q = U x A x delta T Where: Q = heat transfer rate in Btu/hour U = overall heat transfer coefficient A = surface area in square feet delta T = temperature difference across surface; T-inside – T-outside The modeling provided various options of individual materials, including insulated metal panels, windows, roof systems, and other building components and assemblies. BSC explored various magnitudes of relevant change in the respective materials for the purpose of providing educated choices to guide the design process. As an example, using insulated metal panels (IMPs), various insulated metal panel thicknesses were modeled to determine an optimized performance solution. What is important to note about the BSC calculations is that these percentages of calculated improvements were on thermal performance of individual materials (walls, windows, roof systems) and not whole-building percentages of improvement. These calculations of percentages of thermal improvements were then used by Biome Studios for correlation to energy-cost savings and whole-building energy efficiency modeling. The Hickory Consortium, per LEED® 3.0 (2009) requirements, calculated the baseline building performance rating according to the whole-building performance rating method in Appendix G of ANSI/ASHRAE/ IESNA Standard 90.1-2007 (with errata but without addendum 1, using a computer simulation model for the whole-building project. The resulting energy models demonstrated an overall energy efficiency improvement of 50% over baseline with a 72-degree point set. Based on requirements for LEED® Energy and Atmosphere Credit 1 (Optimize Energy Performance), the Castle Square whole-building energy modeling demonstrated more than the 26% energy cost savings, qualifying the project for the maximum of 10 credit points. Whole-building predictive energy modeling was conducted on Castle Square; and as discussed later in this paper, there were inconsistencies in the predictive values and actual use values after one year of reporting. Note: ASHRAE 90.1-2004, Appendix G1.2.2 Neither the proposed building performance nor the baseline building performance are predictions of actual energy consumption or costs for the proposed design after construction. Actual experience will differ from these calculations due to variations such as occupancy, building operation and maintenance, weather, energy use not covered by this procedure, changes in energy rates between design of the building and occupancy, and the precision of the calculation tool. The exterior overcladding (including windows) was predicted to increase the building’s insulation value by a factor of ten, which—in combination with air seal- 2 1 4 • B e r t r a m 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 ing—reduces Castle Square’s annual heating and cooling needs by 61% and 68%, respectively. The calculation—along with a new, more-efficient boiler and the addition of a solar thermal system—predicted 72% total energy savings over baseline, including a new solar hot-water thermal system (Figure 2). The extensive energy modeling calculated the building’s heating requirement and determined a smaller mechanical system. The savings in the new mechanical systems costs helped pay for the superinsulated shell and air sealing that helped reduce the building’s heating and cooling requirements. See Figure 3. It is also worth mentioning that in the post-project analysis of the predicted energy savings versus one year of actual energy use, several data points needed correction in the energy modeling; and that work, as of this writing, was still in development. Air and Joint Seali ng Air testing of the existing structures was required (per LEED®) of the first six midrise apartments with additional verification of the air leakage target by sampling approximately 10% of apartments. Testing included blower door testing per ASTM E779-10. The existing building testing became the baseline for energy-efficiency airtightness improvement. Air testing, plans review, and visual inspections were conducted to determine air-sealing strategies. Extensive internal air sealing was specified and applied between individual apartments and between the apartments and outdoors. Renovations of apartment corridors, trash closets, elevator vestibules, and other rooms were specified to achieve continuous enclosure air barriers. Limiting of air leakage into (or out of) the space and verification of air leakage control were achieved through various testing. The team opened walls and windowsills and cored the roof. Scopes were run through the ductwork. BSC also conducted blower door testing. Assemblies modified or added as part of the renovation scope were constructed to be air-, smoke-, and gas-tight. Interior demising walls were opened at a point where spray foam insulation could be blown in for additional thermal and acoustical performance. Super Insulated Metal Panelized Shell The design team recommended a DER to the tenant organization, including recladding the exterior of the midrise units of the Castle Square project with superinsulated metal panelized shell. Several insulated cladding systems were modeled and evaluated with IMPs selected as the final cladding solution. IMPs are factory-assembled (off-site) wall and roof cladding components typically consisting of a polyisocyanurate insulation core encapsulated between interior and exterior steel skins with factory-formed joints, providing a homogeneous installation. Mineral fiber insulation options are available but are primarily used for firewall performance with a lower R-value per inch. Thermal continuity and performance are achieved across the entire building envelope, and the span 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 B e r t r a m • 2 1 5 Figure 2 – Castle Square midrise deep-energy retrofit costs. Figure 3 – Cost of the superinsulated metal panel shell. Total Costs Costs Costs per Sq. Ft. per Apartment Total cost – Super-insulated shell; $2,499,000 $34.71 $13,016 72,000-sq.-ft. wall area Cost Breakdown Air vapor barriers $125,000 $1.74 $652 Metal panel furring materials $145,000 $2.01 $755 Metal panel furring labor $175,000 $2.44 $915 Mineral wool suppression materials $108,000 $1.50 $563 Mineral wool suppression labor $72,000 $1.00 $376 Metal panel systems materials $1,040,000 $14.44 $5,417 Metal panel systems installation $620,000 $8.61 $3,229 Note: Avoided masonry repairs -300,000 capability of the composite panel allows attachment to steel framing with minimal thermal bridging. Regarding reported IMP R/U-values, ASTM 1363, Thermal Performance of Building Materials and Envelope Assemblies by Means of a Hot Box Apparatus, is the standard for determining the U-value of the IMP and requires a test specimen to include the effect of joint details between adjacent panels. ASTM C518, Standard Test Method for Steady-State Thermal Transmission at a Mean Temperature of 75 Deg. F., is also used for R-value reporting. The IMPs are also approved for NFPA 285, Standard Fire Test Method for Evaluation of Fire Propagation Characteristics of Exterior Nonload-Bearing Wall Assemblies Containing Combustible Components. The two seven-story buildings of the complex (Figure 4) were literally wrapped in the superinsulated shell. The IMPs were specified as R-40 (5 in.)—twice what current code required—applied directly over existing exterior concrete and brick. The IMP interlocking joint is designed to control rainwater penetration and thermal continuity. The joint design incorporates a pressure equalization chamber that also minimizes thermal bridging with superior airtightness. The pressure equalization chamber is shielded from outside by an overlap between two impermeable panel facings, thus minimizing rainwater passage into the joint, driven by gravity and air pressure difference. Intercepted rainwater is drained effectively back to the exterior. See Figures 5 and 6. IMPs for Castle Square utilized a secondary water-resistive barrier (WRB) and air barrier behind the panels. Fundamental to this design is that the primary control layers for water management and air flow control are located behind the IMP, and all materials inboard of these control layers are considered interior of the building. The IMP functions as both the exterior cladding system and primary thermal resistance 2 1 6 • B e r t r a m 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 Figure 4 – A plan rendering of the Castle Square Apartments. Figure 6 – BSC diagram of superinsulated exterior wall system at Castle Square Apartments. Figure 5 – Horizontal support detail. layer. Continuity of the thermal insulation is maintained between the control layers and the back of the IMP with the addition of mineral fiber insulation. This system design has built-in, up-front redundancies for optimized performance. Water management is through a dedicated WRB installed behind the IMPs with 1½-in.-thick mineral fiber, fire-resistant insulation installed horizontally in 2- x 4-ft. panels between furring rows (Figure 7). All flashings and interfaces with the other enclosure elements must be connected to the WRB. While the mineral fiber insulation will reduce the potential for drainage, concerns of water retention in the system are minimal. The airflow control is maintained through an air barrier that is continuous with all other enclosure elements and located exterior of the existing structure. A single, integrated, self-adhered and liquidapplied membrane/air barrier system can be integrated as the WRB system to perform both functions. Inward vapor drive is predominantly controlled by the impermeability of the IMP; however, due to the potential for air movement behind the panels, alternate control layers could be included at the WRB location (such as through the use of a vapor-impermeable SBS membrane). Alternatively, the enclosure can be designed based on a vapor “flow-through approach” to allow for unrestricted diffusion inwards (i.e., no interior Class I or Class II vapor retarder), and a vapor-permeable WRB and air barrier can be used (not recommended if interior vapor barriers or low-permeability materials are currently in the existing wall assembly). Outward vapor control is achieved by controlling the condensing surface temperature. Unlike the first approach (using the IMP as the complete enclosure), the condensing surface in this assembly is behind the WRB and air barrier. This configuration typically provides even less risk of condensation accumulation in the assembly. Vapor management is maintained through the fundamental nature of the panel. Inward vapor drive is controlled by the impermeable nature of the IMP exterior skin. Outward vapor control and condensation resistance are maintained through control of the condensing surface temperature. With the panel installed over a previously uninsulated building, there would be no concerns of interstitial condensation in any climate zone for any commonly available panel thickness. (See Figure 8.) Hygrothermal THERM and WUFI models are helpful in understanding an optimized design as described above. One recommendation is to model a worst-case scenario to 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 B e r t r a m • 2 1 7 Figure 7 – Horizontal IMP detail. Figure 8 – Sections of panels at horizontal and vertical joints. establish a conservative performance recommendation. A field mock-up was constructed per the architect’s direction to include window, flashing, waterproofing of joints, anchorage systems, sealants, edge conditions, closures, and other details as may be required for a weathertight installation. This was not a “functional” model, and it was used to visually demonstrate how the assembly should be constructed. The emerging building enclosure ASTM practice of Building Enclosure Commissioning (BECx), which includes functional performance testing entailing both mock-up and installed work (field) testing would have been ideal for this project. This practice is intended to identify baselevel mock-up and field testing for both fundamental and enhanced commissioning for each of four primary performance categories: thermal, acoustic, resistance to water penetration, and air infiltration/exfiltration. Other Ke y Envel ope Comp onents Accent and fascia panels. Aluminum composite accent and fascia panels were specified to be installed over the fluidapplied air/vapor barrier membrane. The panels were fabricated from 4-mm aluminum composite material with polyethylene core. Windows. The casement windows were specified with an R-5, double-glazed with Argon gas, ASTM E774, Class A, with highperformance and low-emissivity coatings. The roof. Existing roof assemblies consisted of mechanically attached EPDM installed over 2.8-in. polyisocyanurate insulation. The roof decks were castin- place concrete. The existing EPDM membrane was removed by slicing the membrane on two sides of the seam attachment, leaving 6-8 in. of membrane in place, along with the insulation. The existing stone ballast and flashing were removed. New tapered polyiso was installed over the existing flat polyisocyanurate insulation to achieve R-40. On midrise roofs, insulation was provided approximately 10 in. up the penthouse walls and to secondlevel decks to match the thickness of new insulated wall panels. See Figure 10. Thermoplastic single-ply (TPO) membrane roofing was specified with a .060 mechanically attached field sheet. The flashing sheet was .060 TPO with an exposed face color (Energy White). Each building has 756 sq. ft. of solar thermal hot-water collectors on the roof. Currently, the energy offsets of those collectors that should increase total energy savings are being recalculated due to several nonfunctioning units (that have since been corrected) and errors in the modeling that were found during the one-year analysis. Mid Rise Deep -Energ y Retr ofit One-Year Res ults Preliminary gas consumption data from June 2012 to July 2013 show that rather than achieving 65% annual gas savings (as per design projections), the buildings are currently achieving 53% annual gas savings. (See Figure 12.) This is an improvement on the 48% annual gas savings that was reported in March 2013 and the 51% annual savings reported in May 2013. (Note: Data were normalized for weather 2 1 8 • B e r t r a m 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 Figure 9 – A liquid air barrier over the original brick with fire-resistant insulation, window, and superinsulated metal panel installation. Figure 10 – Roof area. Roof Area Existing Insulation N ew Overlay Insulation Attachment Method Midrise upper 2 in. exp. polystyrene 5 in. polyisocyanurate Mechanically fastened Midrise penthouses 2 in. exp. polystyrene 5 in. polyisocyanurate Mechanically fastened Midrise plaza decks 3.2 in. polyisocyanurate* Tapered polyisocyanurate Mechanically fastened B uilding 26/27 2.8 in. polyisocyanurate 5 in. polyisocyanurate Mechanically fastened *Removed and replaced with tapered insulation, 1/8 in. per ft. slope. so that this year’s data could be compared to annual gas consumption from 2008-2010.) The design projection of 65% total reduction in gas consumption (heat and hot-water savings) is being reevaluated due to performance issues related to the solar thermal system. (See Figure 13.) Heat design projections predicted 71% total heating savings. In reality, heating savings between October 2012 and May 2013 ranged from 48% to 64%, depending on the month and the building. Hot-water design projections predicted hot-water savings of 56%. In reality, hot-water savings in the summer of 2013 (after the solar thermal system was repaired) were 55%. During the postconstruction period, meters were not correctly reading data until about June 2012. 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 B e r t r a m • 2 1 9 Figure 11 – Castle Square midrise units with superinsulated cladding, new R-5 windows, highly reflective TPO roof, and solar collector for hot water. Figure 12 – Midrise gas projections. What Caused Differe nces Bet wee n Predicted and Act ual Energ y Efficie ncy? Although the midrise buildings aren’t reporting their 65% gas savings design target, there is opportunity to get closer to targeted energy savings goals. The predicted energy modeling savings were based on a lower design temperature (68 degrees) than actual, which was 71 degrees. What is Happe ning on the Heati ng Side ? First, a decision was made by the residents of Castle Square to operate the building at a much higher temperature than it was designed for. Petersen Engineering assumed a boiler set point to deliver 71-degree heat to apartments. Because of resident demand, a decision was made (without notification to all members of the team) in December 2011 to deliver 75-degree heat to residents despite the average cost increase of $77,000 or half of the projected gas savings! Resident request for this higher temperature was likely due to somewhat uncomfortable conditions in the apartments, because the shell was not complete and construction was still under way. Unfortunately, this higher temperature was maintained after construction completion. Thermostats weren’t limited to 72 degrees until the following year—January 2012. This higher temperature set point affected gas consumption for five of the nine heating season months in the analyzed year. Some residents continue to override their thermostats to enjoy tropical conditions in their apartments. The primary issue impacting heat savings goals is opened windows. Despite being able to control their heat using Energy Star thermostats and an excellent ventilation system, residents frequently leave their windows open, even in freezing temperatures. Finally, the commissioning agent identified some other issues in the midrise heating plants that could be tweaked to improve performance (complicated boiler controls, etc.). Originally, the project did not have a commissioning agent. One was added to the team in the summer of 2013, over a year after construction was complete, and will have a positive outcome on energy efficiency improvements that will likely change current data reporting to be closer to the predicted performance. What Can Be Done to Impr ove Perf orma nce at This Point? First, CSTO and Winn Management should consider a targeted campaign to strongly encourage residents to keep their windows closed during the heating season. In addition to an educational campaign, perhaps some kind of competition could be held. Second, CSTO and Winn Management should ensure that apartment thermostats are set at the appropriate temperature. Third, CSTO and Winn Management should ensure the boilers are appropriately set and that ongoing monitoring and maintenance are scheduled. Concl udi ng Remar ks Any existing building project that is delivering 50%+ retrofit building energy efficiency improvement is considered a success. Financing was key to this specific project, and federal low-income housing tax credits were available, along with a host of other funding for the renovation that made it possible to deliver. The cost of a deep-energy retrofit can be analyzed in a number of different ways. One way is to analyze total cost of the work (labor and materials) from start to finish. The total cost of the Castle Square deep-energy retrofit was $8,177,783 for 192 apartments or $42,593 per apartment. This includes the cost of everything from the superinsulated metal panels to heating, cooling, and hot-water improvements. The question, “What if you were going to reface/re-side the building anyway?” came up in evaluating project options related to costs and return on investment. The modeled payback on the superinsulated metal panel exterior was estimated at 25 years. Incremental cost is defined as the difference between cost of work that would have been done anyway and the deep-energy retrofit scope of work. Castle Square was to be renovated; therefore, the total incremental cost of the deep-energy retrofit at Castle Square was $3,460,486 for 192 apartments or $18,023 per apartment. As indicated 2 2 0 • B e r t r a m 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 Figure 13 – Final incremental cost. Incremental Cost Savings – Therms Savings $ Direct Payback (years) Roof Insulation $45,273 Exterior Wall Insulation (R-40) $2,199,000 Glazing $74,000 Air Sealing $160,000 Subtotal: Enclosure $2,478,273 47,654 $72,911 33.99 Mechanical – Heating & Hot Water $253,800 Ventilation $132,000 Subtotal: Mechanical $385,800 28,077 $42,958 8.98 Solar Thermal $596,413 18,000 $27,540 21.66 TOTAL $3,460,486 93,731 $143,409 24.13 in the Final Increment Cost table (Figure 13), paybacks ranged between 24 and 33.9 years, depending on the specific area of improvement. Castle Square was certified as LEED® Platinum and won the Vanguard Award from the National Affordable Housing Management Association (NAHMA). The Vanguard Award is given each year in order “to recognize newly developed or significantly rehabbed affordable multifamily housing communities that showcase quality design and financing.” Also, Boston Mayor Thomas M. Menino presented the Castle Square Tenants’ Organization and Winn Development with the 2012 Green Residential Award for Sustainability/ Climate Action Leadership. The retrofit of Castle Square Apartments was completed in June 2012, and analysis for further improvement continues. Hopefully, through further evaluation, the goal of Net Zero Energy can someday be achieved. The entire team on this project is to be commended. REFERENCES U.S. Department of Energy’s (DOE) Building America program, http:// www1.eere.energy.gov/buildings/ residential/ba_index.html Castle Square Tenants’ Organization, http://cstoboston.org/ ACEEE: “United Kingdom Tops in Energy Efficiency, U.S. Lags in 9th Place,” http://www.aceee.org/ press/2012/07/aceee-united-kingdom- tops-energy-eff Castle Square Deep Retrofit, http:// www.castledeepenergy.com/ The 2009 McKinsey Global Energy & Materials study, “Unlocking Energy Efficiency in the U.S. Economy,” http://www.mckinsey.com/client_ service/electric_power_and_natural_ gas/latest_thinking/unlocking_energy_ efficiency_in_the_us_economy Metal Construction Association, “Insulated Metal Panels,” http://www. metalconstruction.org/imp/ Design Cost Data (DCD), “Deep Energy Retrofit Profile: Castle Square Apartments on Track to Reduce Energy by 73%,” http://www.dcd. com/insights/insights_nd_2012_1. html Building Science Corporation, “Using Insulated Metal Panels as Part of a Building Enclosure Energy Retrofit,” January 27, 2012 2 9 t h RC I I n t e r n a t i o n a l C o n v e n t i o n a n d T r a d e S h ow • Ma rc h 2 0 – 2 5 , 2 0 1 4 B e r t r a m • 2 2 1
