A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS A Feasibility Study For Market Competitive High Performance Small Office Buildings 00 Introduction 01 What is NZE? October 2015 02 Study Methodology 03 Baseline Definition This study was comissioned by the Sustainable Energy Fund to assess feasibility 04 Baseline Design for the design and construction of a net-zero energy multi-tenant office building 05 NZE Ready Design in the Lehigh Valley area of Pennsylvania. 06 Energy Analysis 07 Cost Analysis 08 Executive Summary 09 Credits We’ve seen net-zero energy (NZE) large office buildings. NREL RESEARCH SUPPORT FACILITY Location: Golden, Colorado Design: RNL Design with Stantec Construction: Haselden Construction Size: 220,000 sf EUI*: 35 kBTU/ft2/year Cost**: $57.4m ($260/ ft2) Net-Zero Energy Certified 2011 *Energy Use Intensity - EUI is a common metric which will be referred to throughout this report. Unless noted otherwise all EUI values are “site” values. This means the amount of energy used on site. “Source” EUI, where noted, accounts for the “site” value plus transmission losses. ** Published Construction Cost 3 | 4 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS And we’ve seen NZE medium office buildings. BULLITT CENTER Location: Seattle, Washington Design: Miller Hull Partnership Construction: Schuchart Construction Size: 50,000 sf EUI*: 16 kBTU/ft2/year Cost**: $18.5m ($370/ft2) Net-Zero Energy Certified 2015 *Energy Use Intensity - EUI is a common metric which will be referred to throughout this report. Unless noted otherwise all EUI values are “site” values. This means the amount of energy used on site. “Source” EUI, where noted, accounts for the “site” value plus transmission losses. ** Published Construction Cost 5 | 6 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS Precedents for NZE small office buildings are harder to come by. RE:VISION ARCHITECTURE, Philadelphia, Pennsylvania 5,000 sf EUI (site) - 24 kBTU/ft2/year LEED-EB Platinum 7 | 8 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS Approximately 1/3* of all commercial office square footage in the United States is found in buildings under 25,000 total square feet. Small office buildings vary wildly in age, context, quality and use. *2012 Commercial Buildings Energy Consumption Survey SYNERGIS TECHNOLOGIES, Quakertown, Pennsylvania 23,000 sf Adaptive reuse of 100 year old manufacturing building 9 | 10 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS This study focuses on a specific kind of small office building - multi-tenant with owner occupancy - and the market feasibility of achieving NZE within this typology. The short story: it can work. For the longer story, read on... BERKS COUNTY COMMUNITY FOUNDATION, Reading, PA 14,800 sf LEED-NC Platinum 11 | 12 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS 01 | What is NZE? The Net-Zero Energy equation is simple: Renewable energy Renewable energy ENERGY GENERATED > ENERGY USED on building on site Getting there is more complicated though. The “net” in Net-Zero refers to the annual period in which Similarly, NREL classifies NZEB’s as follows: energy is calculated. It is acceptable to import energy in some months as long as excess generation in others balances NZEB:A Uses renewable energy sources within the out over the course of a year. building footprint. NZEB:B Uses renewable energy sources within the NREL defines the NZEB (net-zero energy building) renewable project site. (NZEB:A sources may also be energy supply heirarchy in descending order as: used.) 0. Reduce energy demand NZEB:C Includes renewable energy sources off-site to 1. Generate energy within the building footprint generate energy on site. 2. Generate energy within the project site NZEB:D Includes purchased green energy. Renewable energy 3. Generate energy from off-site resources 4. Purchase off-site renewable energy sources If a building does not import any energy in any form (i.e. it is off site “off-grid”) it is classified as ZEB:A Plus 2: Site 13 | 14 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS 02 | Study Methodology To isolate variables and provide a true apples-to- Baseline Envelope & Floor Plan Systems Energy Cost apples comparison, a “baseline” and “NZE Ready” definition Comcheck Snapshot Snapshot version of the same office building program were Baseline Design studied. The baseline design was created in the linear process often Armed with a baseline understanding of energy and cost, used in the marketplace: the architect designs the spatial the Architect, Systems Engineer, and Construction Manager Envelope components to meet the program requirements and then the worked in an unusually integrated and iterative process to arrive buidling systems components are overlayed and adapted. at a NZE Ready design which balanced energy demand Typically, energy modelling is not performed on buildings of reduction, construction cost, and cost of on site renewable this nature. When prescriptive code requirements are not met, energy generation required for NZE. This version of the Systems Energy ComCheck is used to verify and modify the design performance design is referred to as “NZE Ready”; the renewable energy + = NZEB! requirements. system which will make it a net-zero energy building (NZEB) (net-zero energy building) is carried separately in the cost model. For the pupose of this study,the baseline design was run through Cost a full energy model to provide an energy profile that the design team could assess when designing the NZE ready version of the building. The baseline design was also cost NZE Ready Design estimated. 15 | 16 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS 03 | Baseline Definition Single story, “sliced As much glass loaf of bread” as possible What is the market standard (“baseline”) version of a 15,000 sf, owner occupied, multi-tenant building in the Lehigh Valley region? To define the baseline, the Design Team reached out to the as a single story unless it is site constrained. real estate and development community to get a real world 2. As much glass as possible - This was communicated perspective on what actually happens in this particular market. by developers as one of the most desirable features of a We spoke with : Brandywine Realty Trust, CBRE, Dermody space to a prospective tenant. As discussed later, there Granular mechanical Rentable area = Properties, Gorski Engineering, Hankin Group, Jones Lang are better ways of providing daylight and connection; LaSalle, Kaiserman Company, Liberty Property Trust, and NAI. however, the market standard is to provide as much systems useable area glazing as possible. Observations and suggestions about broad design ideas, 3. Granular mechanical systems - The standard is for many preferences, technological integration, and cost management small systems to allow for different space conditioning emerged from the interviews with commercial real estate needs of tenants as well as the ability to reconfigure brokers, builders and developers. Many comments centered units as tenant spaces change. around the ability of the building to be flexible for changing 4. Rentable area = useable area - In the small tenant tenants over time. Six primary requirements were identified for market, paying rent for portions of common spaces is the baseline design: undesirable. 5. Individual suite entrances - This is a desirable feature 1. Single Story, “Sliced Loaf of Bread” - The most for a small tenant as it allows them to appear more flexible way to handle reconfiguring tenant spaces over professional to their clientele. This also allows for the time is a bar shaped building with a rhythmic facade elimination of internal, shared corridors. Individual suite Individual suite kitchens and structure that can be easily reconfigured. All 6. Individual suite kitchens and bathrooms - This is a respondents noted that a building of this size is best market standard condition. entrances and bathrooms 17 | 18 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS Pitched roofs are preferred in this This building has 42% of it’s exterior walls 04 | Baseline Design market for single story buildings. They glazed, which is more than the prescriptive code The baseline design for the 15,000 sf owner occupied, multi-tenant building give an otherwise small building an requirement. In order to meet the performance increased visual presence from the code, continuous “ribbon” windows are used in the Lehigh Valley is a one story bar shaped building. Its form is street and respond to the region’s on the end and rear facades to manage the primarily based on the need for flexibility but also responds to regional vernacular architecture. overall building glazing percentage and the market aesthetic preferences. For the purpose of the study, the baseline glass used has a slightly improved performance design building orientation is assumed to be towards the street becuase specification from code minimums. the standard market response is to face traffic instead of responding to solar conditions. As is standard, different building orientations were averaged to account for unknown site orientation. The entrance facade is broken in to rhythmic panels Brick or masonry exterior walls are favored by the of continuous floor to ceiling storefront glazing. This development community for their long term durability approach maximizes the view and light and provides and reduced maintenance costs. They also are a a flexible framework for future relocation of interior preferred aesthetic in this region’s small office market. tenant partitions 19 | 20 A NET-ZERO APPROACH FOR SMALL OFFICE BUILDINGS Baseline Design Building Envelope Assemblies 1. Roof - Asphalt shingles with plywood roof sheathing, steel roof trusses, R-38* fiberglass attic insulation at base of trusses over drywall ceiling. 2. Opaque walls - Brick veneer w/ 1½” continuous exterior XPS R-7.5, metal studs w/ R-13 fiberglass batt insulation*. 3. Uninsulated 4” concrete slab. 4. Thermally broken aluminum storefront with 1” Low-E insulated glass. No operable windows. * - Code Minimum Baseline Design HVAC Distribution 5.