REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS Bruxelles, March 8, 2012 S.P. Corgnati * , E. Fabrizio § , M. Filippi * § University of Torino * Politecnico di Torino
WHY REFERENCE (BENCHMARK) BUILDING MODELS ? COST OPTIMAL POLICY of the EPBD (European Performance of Buildings Directive) recast 2010/ 31/ EU for the definition of the targets of nearly-zero energy buildings. Draft working document on supplementing Directive 2010/ 31/ EU 1. Selection of reference (benchmark) buildings 2. Definition of energy saving measures for construction 3. Definition of energy saving measures for technical systems 4. Energy calculations (energy requirements) 5. Economic calculations (global cost) 6. Sensitivity analyses and finding of the cost-optimal value What are nearly-zero energy buildings?
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS The methodology 1. 2. & 3. 5. 6. 4.
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS What is a Reference Building? [EPBD recast-Guidelines] Step 1 Step 1 “building characterized by, and representative of, their functionality and Reference Buildings Reference Buildings geographic location, including indoor and outdoor climate conditions” Energy Performance of Buildings Directive Recast (EPBD recast, 2010/ 31/ EU) Each Member State has to define A SET OF REFERENCE BUILDINGS: - 2 for existing buildings; - 1 for new construction . BUILDING CATEGORIES: - Single-family house; - Multi-family house; - Office building; - Non- residential buildings.
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS Approaches to a Reference Building construction Fictional building Input data Model Processing Expert Handbook, manuals, Example RB experience, references aggregated Real RB results Statistical Building Known building manipulation stock stock Theoretical RB separated …. results Problem of the true correlations
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS Step 1 Step 1 Approaches to a Reference Building Reference Buildings Reference Buildings Empirical Data Expert Assumptions Statistical Data REAL BUILDING: a real existing building, with average characteristics based on statistical analysis. EXAMPLE BUILDING : On the basis of experts’ assumption it is the most probable of a group of buildings, within a selected location and age. THEORETICAL BUILDING : A statistical composite of the features found within a category of buildings in the stock (ECBSdefinition).
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS ASSUMPTIONS: Step 1 Step 1 Reference Buildings Reference Buildings 1. System Boundary
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS ASSUMPTIONS: Step 1 Step 1 Reference Buildings Reference Buildings 2. Metrics GLOBAL COST Cost categorisation according to the Framework Methodology (EPBD guidelines) global cost global cost professional fees (e.g. project design) professional fees (e.g. project design) construction of assets construction of assets result of result of taxes (if applicable) taxes (if applicable) energy performance energy performance calculation calculation others (e.g. project others (e.g. project contingencies) contingencies) initial investment cost initial investment cost Standard EN 15459 energy tariffs energy tariffs energy cost energy cost disposal cost disposal cost insurance insurance cyclical regulatory cost cyclical regulatory cost operational cost operational cost utilities utilities annual cost annual cost (except energy cost) (except energy cost) running cost running cost taxes (if applicable) taxes (if applicable) others others maintenance cost maintenance cost inspections inspections adjustments adjustments cleaning cleaning repair repair consumable consumable items items periodic substitute investment periodic substitute investment replacement cost replacement cost of a building element of a building element
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS ASSUMPTIONS: Step 1 Step 1 Reference Buildings Reference Buildings 2. Metrics Lifecycle Standard EN 15459 GLOBAL COST Long Lifecycle are not recommended as it is difficult to predict the interest rates and energy prices. 50 years Lifespan periods of building elements Discount rate? Real interest rate (2,5%) General inflation rate / Inflation rate of energy sources / 1)all the costs refer to the starting year by applying appropriate discount rate coefficients or present value factors; 2)the global cost is the sum of the global costs of initial investment costs, periodic and replacement costs, annual costs and energy costs and the global cost of the final value (negative).
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS ASSUMPTIONS: Step 1 Step 1 Reference Buildings Reference Buildings 3. The boundary conditions: constant parameters Climate Operation & Maintenance Building Occupant envelope behavior Building Indoor equipment environmental conditions Building Performance Energy Needs
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS STATE OF THE ART Step 1 Step 1 Reference Buildings Reference Buildings World: Benchmark Building models developed by US Department of Energy (DOE) Europe: -TABULA project on the definition of residential building typology for energy investigations; -ASIEPI project - BPIE Principles for nearly-zero energy buildings (single-family house, multi-storey building) -Rehva Task Force : “Reference Building for energy performance and cost optimal analysis”. Principles and Application fields of TABULA project Collected national representative single-family houses by ASIEPI project
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS RESEARCH ACTIVITIES BY TEBE GROUP Step 1 Step 1 Reference Buildings Reference Buildings Definition of three Reference Buildings: A Multi-family residential building (Source: TABULA project) 1 A Medium Office Building (Source: ENEA survey over the definition 2 of a representative Italian office building for three main areas) A Large Office Building as result of a customization of the DOE large office 3 building to Italian context (legislative requirements, constructions, climate) Reference buildings collected by age:
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS Real Step 1 Step 1 MULTI-FAMILY REFERENCE BUILDING Reference Buildings Reference Buildings Building External dimensions 12,60 x 37,50 m 472,50 m 2 Gross Floor Area 1336 m 2 Total Gross Area Room height 3,10 m N-E Façade Exterior wall area 170,10 m 2 Geometry S-E Façade Exterior wall area 383,70 m 2 Window area 122,58 m 2 BUILDING S-O Façade Exterior wall area 170,10 m 2 326,30 m 2 N-O Façade Exterior wall area 94,06 m 2 Window area Opaque elements Exterior Wall 0,52 W/ m 2 K 2,02 W/ m 2 K Flat ceiling under the roof Envelope Slab towards non conditioned Components 1,35 W/ m 2 K basement 3,51 W/ m 2 K Transparent Window Elements Gas boiler with radiators. Heating SYSTEM The setpoint temperatures are 20°C from 7 a.m. until 8 p.m., and system 18°C during the remaining hours. Ventilation The infiltration rate is 0,5 ACH and is constant during all days. OPERATION People 0,04 person/ m 2 Internal Gains Appliance (incl. Lighting) 4 W/ m 2 Typical floor plan, Multi-family building.
REFERENCE BUILDINGS FOR COST-OPTIMAL ANALYSIS MEDIUM OFFICE REFERENCE BUILDING Theoretical Step 1 Step 1 External dimensions 16x30 m Reference Buildings Reference Buildings Building 480 m 2 Gross Floor Area 2400 m 2 Total Gross Area Height 2,9 m 278 m 2 Northern Façade Exterior wall area 157,50 m 2 Window area Geometry 278 m 2 Southern Façade Exterior wall area BUILDING 157,50 m 2 Window area Western Façade Exterior wall area 232 m 2 Window area 140 m 2 Eastern Façade Exterior wall area 232 m 2 Window area 140 m 2 0,761 W/ m 2 K Opaque elements Exterior Wall 0,828 W/ m 2 K Roof Envelope Components 0,516 W/ m 2 K Underground slab 3,19 W/ m 2 K Transparent Elements Window HVAC 4 pipes fancoils with outside air Heating system Gas boiler (80°C) 21,5°C from 5 a.m. until 6 p.m., and 15°C in remaining hours, during Axonometric View, Medium office building. Heating setpoint week days. SYSTEM Cooling system Water-cooled chiller 26°C from 5 a.m. until 6 p.m. during week day; Cooling setpoint Turn off during the remaining hours. 11 l/ s per person, Ventilation Air flow is assumed to be constant from 5 a.m. until 6 p.m during week days. The occupancy rate for offices id 0,06 person/ m 2 . People OPERATION 13 W/ m 2 during working days. A 0,5 percentage is assumed Internal Gains Lighting during weekends and night time for security systems. 10 W/ m 2 during working days. Equipm ent Typical floor plan, Medium office building.
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