Challenges_NN2 to_PRP decarbonizing_AJ0 post-war_AJ0 buildings_NN2 
Buildings_NN2 of_PRF the_AT0 mid-twentieth_ORD century_NN1 face_NN1 several_DT0 specific_AJ0 hurdles_NN2 to_PRP successful_AJ0 reuse_NN1 ._SENT The_AT0 integration_NN1 of_PRF building_NN1 structure_NN1 and_CJC enclosure_NN1 is_VBZ one_CRD such_DT0 challenge_NN1 ._SENT The_AT0 advancement_NN1 of_PRF concrete_NN1 as_PRP a_AT0 building_NN1 material_NN1 through_PRP the_AT0 early_AJ0 twentieth_ORD century_NN1 led_VVD to_PRP the_AT0 dissolution_NN1 of_PRF the_AT0 idea_NN1 of_PRF separate_AJ0 internal_AJ0 frame_NN1 and_CJC exterior_NN1 wall_NN1 systems_NN2 and_CJC the_AT0 emergence_NN1 of_PRF the_AT0 monolithic_AJ0 frame_NN1 ._SENT Particularly_AV0 in_PRP Brutalist_AJ0 design_NN1 ,_PUN concrete_NN1 was_VBD not_XX0 only_AV0 used_VVN as_PRP a_AT0 concealed_AJ0 structural_AJ0 material_NN1 ,_PUN but_CJC it_PNP was_VBD also_AV0 celebrated_VVN and_CJC expressed_VVN as_PRP part_NN1 of_PRF the_AT0 building_NN1 envelope_NN1 ._SENT This_DT0 application_NN1 of_PRF concrete_NN1 poses_VVZ dual_AJ0 conservation_NN1 and_CJC energy_NN1 efficiency_NN1 challenges_NN2 ._SENT From_PRP a_AT0 conservation_AJ0 standpoint_NN1 ,_PUN concrete_NN1 exposed_VVN to_PRP the_AT0 elements_NN2 is_VBZ highly_AV0 vulnerable_AJ0 to_PRP water_NN1 infiltration_NN1 and_CJC temperature_NN1 variation_NN1 ._SENT Over_PRP time_NN1 ,_PUN this_DT0 exposure_NN1 will_VM0 target_VVI any_DT0 original_AJ0 material_NN1 imperfections_NN2 ,_PUN ranging_VVG from_PRP reactive_AJ0 aggregate_NN1 to_PRP under_AV0 reinforcing_VVG to_PRP inadequate_AJ0 cover_NN1 of_PRF ferrous_AJ0 element_NN1 ,_PUN causing_VVG progressive_AJ0 deterioration_NN1 of_PRF the_AT0 façade_NN1 ._SENT 
As_AV0 relates_VVZ to_PRP the_AT0 building_NN1 envelope_NN1 ,_PUN this_DT0 integration_NN1 of_PRF structure_NN1 and_CJC façade_NN1 creates_VVZ significant_AJ0 limitations_NN2 to_PRP the_AT0 thermal_AJ0 performance_NN1 of_PRF the_AT0 building_NN1 enclosure_NN1 ._SENT Concrete_AJ0 structure_NN1 directly_AV0 exposed_VVN on_PRP the_AT0 façade_NN1 conducts_VVZ heat_NN1 from_PRP the_AT0 conditioned_AJ0 interior_NN1 to_PRP the_AT0 exterior_NN1 ,_PUN creating_VVG a_AT0 thermal_AJ0 bridge_NN1 that_CJT can_VM0 only_AV0 be_VBI mediated_VVN by_PRP recladding_NN1 or_CJC over-cladding_NN1 ,_PUN an_AT0 approach_NN1 that_CJT applies_VVZ a_AT0 new_AJ0 façade_NN1 assembly_NN1 over_PRP the_AT0 plane_NN1 of_PRF the_AT0 original_AJ0 facade_NN1 ._SENT Even_AV0 when_CJS not_XX0 exposed_AJ0 ,_PUN concrete_AJ0 structural_AJ0 elements_NN2 in_PRP plane_NN1 with_PRP the_AT0 exterior_AJ0 wall_NN1 frequently_AV0 interrupt_VVB existing_AJ0 or_CJC new_AJ0 interior_NN1 insulation_NN1 at_PRP columns_NN2 and_CJC floor_NN1 slabs_NN2 ;_PUN again_AV0 ,_PUN these_DT0 thermal_AJ0 bridges_NN2 can_VM0 only_AV0 be_VBI eliminated_VVN by_PRP recladding_AJ0 or_CJC overcladding_AJ0 outboard_NN1 of_PRF the_AT0 concrete_AJ0 structure_NN1 ._SENT Cladding_VVG over_AVP or_CJC recladding_VVG original_AJ0 facades_NN2 offers_VVZ the_AT0 opportunity_NN1 to_TO0 both_AV0 protect_VVI exposed_AJ0 structural_AJ0 elements_NN2 and_CJC provide_VVB a_AT0 continuous_AJ0 thermal_AJ0 envelope_NN1 ;_PUN however_AV0 ,_PUN it_PNP challenges_VVZ current_AJ0 heritage_NN1 conservation_NN1 practices_NN2 and_CJC comes_VVZ with_PRP its_DPS own_DT0 upfront_AJ0 carbon_NN1 costs_NN2 that_CJT must_VM0 be_VBI evaluated_VVN for_PRP value_NN1 against_PRP potential_AJ0 improvements_NN2 to_PRP performance_NN1 ._SENT 
There_EX0 are_VBB also_AV0 architectural_AJ0 challenges_NN2 to_PRP upgrading_VVG HVAC_AJ0 systems_NN2 in_PRP post-war_AJ0 buildings_NN2 ._SENT While_CJS they_PNP were_VBD originally_AV0 designed_VVN with_PRP active_AJ0 mechanical_AJ0 systems_NN2 ,_PUN these_DT0 systems_NN2 were_VBD typically_AV0 not_XX0 sized_VVN adequately_AV0 for_PRP current_AJ0 requirements_NN2 ,_PUN and_CJC primary_AJ0 equipment_NN1 is_VBZ at_PRP the_AT0 end_NN1 of_PRF its_DPS life_NN1 ,_PUN if_CJS still_AV0 in_PRP service_NN1 ._SENT Many_DT0 buildings_NN2 of_PRF this_DT0 era_NN1 were_VBD designed_VVN with_PRP a_AT0 structural_AJ0 economy_NN1 that_CJT resulted_VVD in_PRP minimal_AJ0 floor-to-floor_AJ0 heights_NN2 ,_PUN making_VVG horizontal_AJ0 redistribution_NN1 of_PRF systems_NN2 particularly_AV0 challenging_AJ0 ._SENT Additionally_AV0 ,_PUN distribution_NN1 was_VBD often_AV0 concealed_VVN within_PRP concrete_AJ0 structure_NN1 ,_PUN making_VVG it_PNP impossible_AJ0 to_TO0 repair_VVI or_CJC reroute_VVI without_PRP destructive_AJ0 demolition_NN1 ._SENT There_EX0 are_VBB also_AV0 risks_NN2 to_PRP installing_VVG new_AJ0 materials_NN2 and_CJC technologies_NN2 without_PRP sufficient_AJ0 consideration_NN1 for_PRP how_AVQ they_PNP will_VM0 perform_VVI within_PRP the_AT0 existing_AJ0 building_NN1 ._SENT For_PRP example_NN1 ,_PUN components_NN2 such_DT0 as_PRP chilled_AJ0 beams_NN2 and_CJC radiant_AJ0 panels_NN2 may_VM0 see_VVI issues_NN2 with_PRP condensation_NN1 if_CJS environmental_AJ0 conditions_NN2 are_VBB not_XX0 controlled_VVN properly_AV0 ,_PUN and_CJC changing_VVG the_AT0 flow_NN1 of_PRF moisture_NN1 across_PRP a_AT0 building_NN1 envelope_NN1 may_VM0 lead_VVI to_PRP condensation_NN1 and_CJC deterioration_NN1 of_PRF existing_AJ0 material_NN1 to_TO0 remain_VVI ._SENT Creative_AJ0 solutions_NN2 and_CJC a_AT0 thorough_AJ0 understanding_NN1 of_PRF the_AT0 existing_AJ0 building_NN1 are_VBB required_VVN to_TO0 understand_VVI which_DTQ elements_NN2 of_PRF the_AT0 original_AJ0 systems_NN2 may_VM0 be_VBI kept_VVN in_PRP service_NN1 through_PRP retrofit_NN1 ,_PUN where_AVQ new_AJ0 systems_NN2 are_VBB required_VVN ,_PUN and_CJC how_AVQ to_TO0 design_VVI them_PNP appropriately_AV0 ._SENT 
Life_NN1 cycle_NN1 assessment_NN1 approach_NN1 for_PRP building_NN1 reuse_NN1 
Traditionally_AV0 ,_PUN environmental_AJ0 sustainability_NN1 in_PRP building_NN1 reuse_NN1 has_VHZ been_VBN evaluated_VVN based_VVN how_AVQ well_AV0 an_AT0 existing_AJ0 building_NN1 can_VM0 perform_VVI relative_AJ0 to_PRP current_AJ0 standards_NN2 ._SENT Energy_NN1 performance_NN1 ,_PUN while_CJS important_AJ0 ,_PUN only_AV0 captures_VVZ the_AT0 impacts_NN2 from_PRP one_CRD stage_NN1 of_PRF a_AT0 building_NN1 's_POS life_NN1 cycle_NN1 ,_PUN ommitting_VVG the_AT0 environmental_AJ0 footprint_NN1 of_PRF the_AT0 materials_NN2 used_VVN and_CJC construction_NN1 activities_NN2 that_CJT occur_VVB over_PRP a_AT0 building_NN1 's_POS life_NN1 ._SENT Life_NN1 cycle_NN1 assessment_NN1 (_PUL LCA_NP0 )_PUR is_VBZ a_AT0 quantitative_AJ0 accounting_NN1 methodology_NN1 that_CJT predicts_VVZ the_AT0 environmental_AJ0 impacts_NN2 of_PRF a_AT0 material_NN1 or_CJC assembly_NN1 across_PRP the_AT0 entire_AJ0 life_NN1 cycle_NN1 ,_PUN from_PRP material_NN1 extraction_NN1 and_CJC manufacturing_NN1 through_PRP use_NN1 and_CJC end_NN1 of_PRF life_NN1 ._SENT When_CJS this_DT0 analysis_NN1 is_VBZ applied_VVN to_PRP many_DT0 or_CJC all_DT0 of_PRF the_AT0 materials_NN2 that_CJT go_VVB into_PRP a_AT0 building_NN1 ,_PUN this_DT0 is_VBZ referred_VVN to_PRP as_AV0 whole-building_AJ0 life_NN1 cycle_NN1 assessment_NN1 (_PUL WBLCA_NP0 )_PUR ._SENT As_CJS defined_VVN by_PRP ISO_NP0 14040_CRD ,_PUN the_AT0 international_AJ0 framework_NN1 for_PRP life_NN1 cycle_NN1 assessment_NN1 ,_PUN the_AT0 process_NN1 of_PRF performing_VVG a_AT0 LCA_NN1 involves_VVZ four_CRD phases_NN2 :_PUN 
Goal_NN1 and_CJC scope_NN1 definition_NN1 :_PUN understand_VVB what_DTQ the_AT0 results_NN2 of_PRF the_AT0 assessment_NN1 will_VM0 be_VBI used_VVN for_PRP and_CJC thus_AV0 which_DTQ materials_NN2 or_CJC assemblies_NN2 are_VBB important_AJ0 to_TO0 include_VVI and_CJC to_PRP what_DTQ level_NN1 of_PRF detail_NN1 ._SENT 
Inventory_NN1 analysis_NN1 :_PUN create_VVB an_AT0 accounting_NN1 of_PRF all_DT0 the_AT0 materials_NN2 and_CJC activities_NN2 that_CJT contribute_VVB to_PRP the_AT0 scope_NN1 defined_VVN in_PRP Step_NN1 1._CRD This_DT0 includes_VVZ ,_PUN but_CJC is_VBZ not_XX0 limited_AJ0 to_TO0 ,_PUN the_AT0 bill_NN1 of_PRF materials_NN2 used_VVN in_PRP a_AT0 building_NN1 or_CJC portion_NN1 of_PRF the_AT0 building_NN1 being_VBG evaluated_VVN ._SENT 
Impact_NN1 assessment_NN1 :_PUN calculate_VVB environmental_AJ0 impacts_NN2 by_PRP applying_VVG environmental_AJ0 impact_NN1 factors_NN2 to_PRP the_AT0 inventory_NN1 created_VVN in_PRP Step_NN1 2._CRD This_DT0 is_VBZ most_AV0 simply_AV0 done_VDN using_VVG tools_NN2 that_CJT include_VVB building-specific_AJ0 data_NN0 but_CJC can_VM0 also_AV0 be_VBI performed_VVN manually_AV0 using_VVG open-source_AJ0 data_NN0 sets_NN2 ._SENT 
Interpretation_NN1 :_PUN analyze_VVB and_CJC understand_VVB the_AT0 results_NN2 to_TO0 draw_VVI conclusions_NN2 and_CJC respond_VVB to_PRP the_AT0 goals_NN2 defined_VVN in_PRP Step_NN1 1._CRD 
Life_NN1 cycle_NN1 assessment_NN1 can_VM0 be_VBI applied_VVN to_PRP existing_AJ0 buildings_NN2 to_TO0 measure_VVI and_CJC reduce_VVI the_AT0 impact_NN1 of_PRF renovation_NN1 and_CJC to_TO0 quantify_VVI the_AT0 avoided_VVN impacts_NN2 of_PRF renovation_NN1 compared_VVN to_PRP new_AJ0 construction_NN1 ._SENT In_PRP both_DT0 cases_NN2 ,_PUN it_PNP is_VBZ critical_AJ0 to_TO0 create_VVI a_AT0 meaningful_AJ0 scope_NN1 boundary_NN1 ._SENT Existing_AJ0 building_NN1 fabric_NN1 that_CJT will_VM0 remain_VVI in_PRP place_NN1 constitutes_VVZ a_AT0 '_PUQ sunk_AJ0 cost_NN1 '_POS and_CJC can_VM0 be_VBI excluded_VVN from_PRP the_AT0 analysis_NN1 ;_PUN those_DT0 embodied_VVD carbon_NN1 emissions_NN2 were_VBD released_VVN in_PRP the_AT0 past_NN1 and_CJC are_VBB not_XX0 impacted_VVN by_PRP reusing_VVG the_AT0 building_NN1 ._SENT The_AT0 environmental_AJ0 impacts_NN2 that_CJT do_VDB occur_VVI from_PRP renovation_NN1 are_VBB related_VVN to_PRP the_AT0 new_AJ0 material_NN1 we_PNP add_VVB to_PRP buildings_NN2 as_CJS well_AV0 as_CJS the_AT0 demolition_NN1 and_CJC end-of-life_AJ0 treatment_NN1 of_PRF material_NN1 that_CJT we_PNP remove_VVB –_PUN these_DT0 added_VVD and_CJC subtracted_VVD materials_NN2 are_VBB ,_PUN therefore_AV0 ,_PUN the_AT0 materials_NN2 that_CJT are_VBB critical_AJ0 to_TO0 include_VVI in_PRP the_AT0 inventory_NN1 to_TO0 measure_VVI the_AT0 impact_NN1 of_PRF renovation_NN1 ._SENT This_DT0 paper_NN1 illustrates_VVZ two_CRD ways_NN2 in_PRP which_DTQ LCA_NN1 can_VM0 be_VBI applied_VVN to_PRP building_NN1 reuse_NN1 :_PUN the_AT0 first_ORD ,_PUN to_TO0 quantify_VVI the_AT0 avoided_VVN impacts_NN2 –_PUN in_PRP this_DT0 case_NN1 the_AT0 carbon_NN1 emissions_NN2 that_CJT are_VBB saved_VVN –_PUN by_PRP reusing_VVG and_CJC upgrading_VVG an_AT0 existing_AJ0 building_NN1 instead_AV0 of_PRF replacing_VVG it_PNP ;_PUN and_CJC the_AT0 second_ORD ,_PUN to_TO0 make_VVI decisions_NN2 about_PRP the_AT0 lowest-carbon_AJ0 approach_NN1 for_PRP reusing_VVG a_AT0 specific_AJ0 building_NN1 ._SENT 
It_PNP is_VBZ important_AJ0 to_TO0 note_VVI that_CJT LCA_NP0 is_VBZ not_XX0 an_AT0 exact_AJ0 science_NN1 ._SENT While_CJS there_EX0 are_VBB standards_NN2 and_CJC product_NN1 category_NN1 rules_NN2 in_PRP place_NN1 ,_PUN inconsistencies_NN2 and_CJC uncertainties_NN2 exist_VVB with_PRP LCA_NN1 data_NN0 ,_PUN with_PRP tools_NN2 ,_PUN and_CJC in_PRP the_AT0 methodology_NN1 with_PRP which_DTQ these_DT0 are_VBB applied_VVN to_PRP individual_AJ0 projects_NN2 ._SENT For_PRP example_NN1 ,_PUN some_DT0 materials_NN2 have_VHB only_AJ0 industry_NN1 average_NN1 data_NN0 rather_AV0 than_CJS product_NN1 specific_AJ0 data_NN0 ,_PUN and_CJC different_AJ0 manufacturers_NN2 may_VM0 include_VVI different_AJ0 life_NN1 cycle_NN1 stages_NN2 in_PRP their_DPS numbers_NN2 ._SENT Data_NN0 includes_VVZ assumptions_NN2 about_PRP what_DTQ happens_VVZ to_PRP a_AT0 given_AJ0 material_NN1 over_PRP its_DPS life_NN1 cycle_NN1 ,_PUN from_PRP how_AVQ often_AV0 it_PNP must_VM0 be_VBI refurbished_VVN or_CJC replaced_VVN to_PRP what_DTQ happens_VVZ at_PRP the_AT0 end_NN1 of_PRF its_DPS life_NN1 ._SENT There_EX0 are_VBB also_AV0 questions_NN2 about_PRP how_AVQ to_TO0 count_VVI biogenic_AJ0 carbon_NN1 ,_PUN emissions_NN2 associated_VVN with_PRP the_AT0 natural_AJ0 carbon_NN1 cycle_NN1 of_PRF materials_NN2 like_PRP wood_NN1 that_CJT sequester_NN1 carbon_NN1 as_CJS they_PNP grow_VVB and_CJC then_AV0 release_VVB it_PNP at_PRP end_NN1 of_PRF life_NN1 ._SENT LCA_NN1 for_PRP existing_AJ0 buildings_NN2 introduces_VVZ its_DPS own_DT0 set_NN1 of_PRF challenges_NN2 ._SENT Data_NN0 can_VM0 be_VBI more_AV0 difficult_AJ0 to_TO0 obtain_VVI for_PRP traditional_AJ0 building_NN1 materials_NN2 and_CJC techniques_NN2 ._SENT Additionally_AV0 ,_PUN most_DT0 LCA_NN1 software_NN1 tools_NN2 are_VBB created_VVN with_PRP new_AJ0 construction_NN1 in_PRP mind_NN1 ._SENT While_CJS these_DT0 limitations_NN2 lead_VVB to_PRP a_AT0 margin_NN1 of_PRF error_NN1 in_PRP LCA_NN1 results_NN2 ,_PUN the_AT0 analysis_NN1 is_VBZ still_AV0 highly_AV0 valuable_AJ0 as_CJS a_AT0 comparative_AJ0 assessment_NN1 technique_NN1 and_CJC is_VBZ the_AT0 only_AV0 accepted_AJ0 methodology_NN1 for_PRP calculating_VVG life_NN1 cycle_NN1 environmental_AJ0 impacts_NN2 ._SENT LCA_NP0 is_VBZ the_AT0 basis_NN1 of_PRF many_DT0 embodied_VVN carbon_NN1 policies_NN2 and_CJC is_VBZ incorporated_VVN as_PRP a_AT0 requirement_NN1 into_PRP many_DT0 green_AJ0 building_NN1 rating_NN1 systems_NN2 ,_PUN including_PRP LEED_NP0 ,_PUN BREEAM_NP0 ,_PUN and_CJC LBC_NP0 ._SENT 
Case_NN1 study_NN1 :_PUN quantifying_VVG the_AT0 carbon_NN1 savings_NN2 potential_NN1 of_PRF whole_AJ0 building_NN1 reuse_NN1 
The_AT0 first_ORD case_NN1 study_NN1 presented_VVN here_AV0 is_VBZ a_AT0 residence_NN1 hall_NN1 at_PRP MIT_NN1 designed_VVN by_PRP Josep_NP0 Lluis_NP0 Sert_NP0 in_PRP 1974_CRD (_PUL Figure_NN1 1_CRD )_PUR ._SENT The_AT0 115_CRD ,_PUN 000_CRD square_AJ0 foot_NN1 ,_PUN five-story_AJ0 building_NN1 is_VBZ located_VVN on_PRP the_AT0 Charles_NP0 River_NP0 ,_PUN a_AT0 waterfront_NN1 whose_DTQ architecture_NN1 was_VBD influenced_VVN by_PRP Sert_NP0 's_POS academic_AJ0 leadership_NN1 at_PRP Harvard_NP0 's_POS Graduate_NN1 School_NN1 of_PRF Design_NN1 and_CJC own_DT0 design_NN1 work_NN1 of_PRF the_AT0 mid-twentieth_ORD century_NN1 ._SENT The_AT0 residence_NN1 hall_NN1 comprises_VVZ a_AT0 minimal_AJ0 ,_PUN cast-in-place_AJ0 structure_NN1 clad_VVN in_PRP brick_NN1 veneer_NN1 with_PRP exposed_AJ0 concrete_AJ0 slab_NN1 edges_NN2 and_CJC cantilevers_NN2 ,_PUN and_CJC the_AT0 fenestration_NN1 displays_VVZ Sert_NP0 's_POS signature_NN1 multichromatic_AJ0 aluminum_NN1 window_NN1 frames_NN2 ,_PUN although_CJS in_PRP a_AT0 stark_AJ0 black_AJ0 and_CJC white_AJ0 in_PRP this_DT0 application_NN1 ._SENT The_AT0 building_NN1 originally_AV0 functioned_VVN as_PRP three_CRD distinct_AJ0 '_PUQ towers_NN2 '_POS housing_NN1 nine_CRD independent_AJ0 social_AJ0 communities_NN2 ._SENT Over_PRP its_DPS life_NN1 ,_PUN the_AT0 building_NN1 retained_VVD the_AT0 same_DT0 programmatic_AJ0 use_NN1 ;_PUN however_AV0 ,_PUN changing_VVG residential_AJ0 approaches_NN2 ,_PUN community_NN1 sizes_NN2 ,_PUN and_CJC expectations_NN2 of_PRF comfort_NN1 and_CJC performance_NN1 in_PRP conjunction_NN1 with_PRP aging_AJ0 systems_NN2 and_CJC envelope_NN1 components_NN2 had_VHD rendered_VVN the_AT0 building_NN1 in_PRP need_NN1 of_PRF renovation_NN1 and_CJC upgrade_NN1 ._SENT 
The_AT0 student_NN1 groups_NN2 living_VVG in_PRP the_AT0 building_NN1 felt_VVD a_AT0 strong_AJ0 affinity_NN1 for_PRP the_AT0 architecture_NN1 of_PRF their_DPS home_NN1 ._SENT However_AV0 ,_PUN there_EX0 were_VBD tensions_NN2 between_PRP the_AT0 rigidity_NN1 of_PRF the_AT0 existing_AJ0 building_NN1 and_CJC the_AT0 evolving_AJ0 needs_NN2 of_PRF the_AT0 students_NN2 living_VVG within_PRP it_PNP ._SENT The_AT0 three_CRD towers_NN2 of_PRF the_AT0 building_NN1 were_VBD connected_VVN only_AV0 via_PRP a_AT0 corridor_NN1 at_PRP the_AT0 ground_NN1 floor_NN1 ,_PUN leaving_VVG communities_NN2 physically_AV0 isolated_VVN from_PRP one_CRD another_DT0 ._SENT Additionally_AV0 ,_PUN as_CJS community_NN1 sizes_NN2 grew_VVD and_CJC shrank_VVD over_PRP time_NN1 ,_PUN the_AT0 distribution_NN1 of_PRF amenities_NN2 became_VVD skewed_AJ0 with_PRP some_DT0 communities_NN2 physically_AV0 disconnected_VVN from_PRP their_DPS assigned_AJ0 common_AJ0 spaces_NN2 ,_PUN which_DTQ has_VHZ led_VVN a_AT0 lack_NN1 of_PRF equity_NN1 ._SENT 
Physically_AV0 ,_PUN the_AT0 building_NN1 was_VBD facing_VVG systems_NN2 at_PRP the_AT0 end_NN1 of_PRF their_DPS service_NN1 life_NN1 and_CJC deterioration_NN1 and_CJC aging_NN1 of_PRF exterior_AJ0 components_NN2 ._SENT The_AT0 original_AJ0 heating_NN1 and_CJC cooling_AJ0 system_NN1 consisted_VVD of_PRF a_AT0 two-pipe_AJ0 hydronic_AJ0 system_NN1 fed_VVN from_PRP a_AT0 central_AJ0 plant_NN1 ,_PUN with_PRP a_AT0 local_AJ0 chiller_NN1 ._SENT The_AT0 building_NN1 was_VBD not_XX0 mechanically_AV0 ventilated_VVN ,_PUN relying_VVG on_PRP operable_AJ0 aluminum_NN1 ,_PUN single-glazed_AJ0 windows_NN2 for_PRP fresh_AJ0 air_NN1 ._SENT The_AT0 original_AJ0 envelope_NN1 was_VBD brick_NN1 veneer_NN1 on_PRP metal_NN1 studs_NN2 ,_PUN with_PRP a_AT0 small_AJ0 amount_NN1 of_PRF batt_NN1 insulation_NN1 in_PRP the_AT0 stud_NN1 cavity_NN1 ;_PUN roofs_NN2 were_VBD entirely_AV0 uninsulated_AJ0 ._SENT Additionally_AV0 ,_PUN all_DT0 the_AT0 building_NN1 's_POS MEP_NP0 equipment_NN1 was_VBD located_VVN on_PRP the_AT0 first_ORD floor_NN1 ,_PUN which_DTQ will_VM0 become_VVI increasingly_AV0 vulnerable_AJ0 to_PRP flooding_VVG through_PRP the_AT0 coming_AJ0 decades_NN2 ._SENT 
After_CJS more_AV0 than_CJS forty_CRD years_NN2 with_PRP only_AJ0 minor_AJ0 renovations_NN2 ,_PUN the_AT0 building_NN1 needed_VVD a_AT0 comprehensive_AJ0 renewal_NN1 ._SENT The_AT0 renovation_NN1 project_NN1 included_VVD new_AJ0 building_NN1 systems_NN2 to_TO0 bring_VVI the_AT0 building_NN1 up_AVP to_PRP modern_AJ0 performance_NN1 standards_NN2 ,_PUN upgrades_NN2 to_PRP the_AT0 building_NN1 envelope_NN1 to_TO0 improve_VVI thermal_AJ0 comfort_NN1 and_CJC reduce_VVB energy_NN1 use_NN1 ,_PUN climate_NN1 resilience_NN1 improvements_NN2 ,_PUN and_CJC interior_AJ0 reconfigurations_NN2 to_TO0 support_VVI equity_NN1 and_CJC flexibility_NN1 in_PRP the_AT0 future_NN1 while_CJS maintaining_VVG the_AT0 original_AJ0 design_NN1 intent_NN1 ._SENT Programmatically_AV0 ,_PUN the_AT0 renovation_NN1 physically_AV0 connected_VVN the_AT0 three_CRD towers_NN2 to_TO0 encourage_VVI strength_NN1 of_PRF community_NN1 and_CJC laid_VVD out_AVP residential_AJ0 groups_NN2 via_PRP a_AT0 series_NN0 and_CJC '_PUQ anchors_NN2 '_PUQ and_CJC '_PUQ flex_NN1 '_POS spaces_NN2 ,_PUN which_DTQ allow_VVB each_DT0 community_NN1 to_TO0 maintain_VVI a_AT0 central_AJ0 heart_NN1 while_CJS accommodating_VVG a_AT0 changing_AJ0 population_NN1 over_PRP time_NN1 ._SENT A_AT0 new_AJ0 circulation_NN1 route_NN1 was_VBD created_VVN through_PRP the_AT0 building_NN1 ,_PUN consolidated_AJ0 amenities_NN2 and_CJC taking_VVG advantage_NN1 of_PRF the_AT0 building_NN1 's_POS daylight_NN1 and_CJC views_NN2 (_PUL Figures_NN2 2_CRD through_PRP 4_CRD )_PUR ._SENT 
The_AT0 exterior_AJ0 restoration_NN1 of_PRF the_AT0 building_NN1 involved_AJ0 repair_NN1 and_CJC localized_AJ0 rebuilding_NN1 of_PRF the_AT0 brick_NN1 masonry_NN1 veneer_NN1 ,_PUN repair_NN1 and_CJC recoating_VVG of_PRF exposed_AJ0 concrete_NN1 ,_PUN and_CJC replacement_NN1 of_PRF the_AT0 failing_AJ0 aluminum_NN1 windows_NN2 with_PRP double-glazed_AJ0 ,_PUN thermally_AV0 broken_AJ0 frames_NN2 ._SENT The_AT0 existing_AJ0 building_NN1 design_NN1 and_CJC condition_NN1 presented_VVN challenges_NN2 to_PRP envelope_NN1 improvement_NN1 ,_PUN including_PRP the_AT0 thermal_AJ0 bridge_NN1 created_VVN by_PRP the_AT0 concrete_AJ0 cantilevers_NN2 and_CJC slabs_NN2 extending_VVG to_PRP the_AT0 outside_AJ0 face_NN1 of_PRF the_AT0 wall_NN1 (_PUL Figure_NN1 5_CRD )_PUR and_CJC the_AT0 unknown_AJ0 condition_NN1 of_PRF the_AT0 original_AJ0 felt_NN1 paper_NN1 air_NN1 barrier_NN1 ._SENT Thermal_AJ0 modeling_NN1 was_VBD performed_VVN during_PRP the_AT0 concept_NN1 phase_NN1 to_TO0 establish_VVI the_AT0 existing_AJ0 thermal_AJ0 resistance_NN1 (_PUL R-Value_NN1 )_PUR of_PRF the_AT0 opaque_AJ0 wall_NN1 and_CJC thermal_AJ0 bridge_NN1 conditions_NN2 and_CJC to_TO0 explore_VVI the_AT0 potential_AJ0 improvements_NN2 in_PRP R-Value_NN1 that_CJT could_VM0 be_VBI achieved_VVN by_PRP filling_VVG the_AT0 stud_NN1 cavity_NN1 or_CJC furring_VVG the_AT0 wall_NN1 out_AVP to_TO0 create_VVI continuous_AJ0 insulation_NN1 inboard_AJ0 of_PRF the_AT0 existing_AJ0 wall_NN1 at_PRP each_DT0 floor_NN1 level_NN1 to_TO0 achieve_VVI current_AJ0 prescribed_AJ0 levels_NN2 of_PRF performance_NN1 ._SENT Hygrothermal_AJ0 modeling_NN1 in_PRP WUFI_NP0 ,_PUN a_AT0 software_NN1 that_CJT calculates_VVZ moisture_NN1 and_CJC heat_NN1 flow_NN1 through_PRP building_NN1 materials_NN2 over_PRP time_NN1 ,_PUN was_VBD then_AV0 completed_VVN to_TO0 evaluate_VVI several_DT0 insulation_NN1 materials_NN2 ,_PUN including_PRP mineral_NN1 wool_NN1 batt_NN1 and_CJC open_AJ0 and_CJC closed_AJ0 cell_NN1 spray_NN1 foam_NN1 to_TO0 ensure_VVI that_CJT the_AT0 proposed_AJ0 solution_NN1 did_VDD not_XX0 introduce_VVI a_AT0 risk_NN1 of_PRF condensation_NN1 ._SENT Ultimately_AV0 ,_PUN due_AJ0 to_PRP factors_NN2 of_PRF human_AJ0 health_NN1 ,_PUN long-term_AJ0 performance_NN1 ,_PUN and_CJC to_TO0 maintain_VVI the_AT0 moisture_NN1 migration_NN1 paths_NN2 of_PRF the_AT0 original_AJ0 wall_NN1 construction_NN1 ,_PUN the_AT0 stud_NN1 cavities_NN2 were_VBD filled_VVN with_PRP mineral_NN1 wool_NN1 and_CJC an_AT0 air-sealed_AJ0 variable_AJ0 permeability_NN1 vapor_NN1 membrane_NN1 was_VBD applied_VVN to_TO0 allow_VVI moisture_NN1 to_TO0 continue_VVI to_TO0 move_VVI through_PRP the_AT0 wall_NN1 similarly_AV0 to_PRP the_AT0 original_AJ0 condition_NN1 ._SENT The_AT0 roofs_NN2 were_VBD insulated_VVN to_PRP code_NN1 ._SENT More_DT0 aggressive_AJ0 envelope_NN1 improvements_NN2 ,_PUN including_PRP additional_AJ0 roof_NN1 insulation_NN1 and_CJC triple_AJ0 glazed_AJ0 windows_NN2 ,_PUN were_VBD evaluated_VVN through_PRP energy_NN1 modeling_NN1 ,_PUN which_DTQ showed_VVD negligible_AJ0 annual_AJ0 energy_NN1 savings_NN2 from_PRP additional_AJ0 upgrades_NN2 ._SENT While_CJS recladding_VVG the_AT0 building_NN1 to_TO0 enable_VVI installation_NN1 of_PRF continuous_AJ0 insulation_NN1 at_PRP the_AT0 exterior_NN1 would_VM0 have_VHI eliminated_VVN the_AT0 existing_AJ0 thermal_AJ0 bridges_NN2 created_VVN by_PRP the_AT0 building_NN1 's_POS structural_AJ0 system_NN1 ,_PUN this_DT0 approach_NN1 was_VBD rejected_VVN due_AJ0 to_PRP impact_NN1 to_PRP historic_AJ0 appearance_NN1 and_CJC cost_NN1 ;_PUN ultimately_AV0 the_AT0 carbon_NN1 payback_NN1 of_PRF this_DT0 scheme_NN1 ,_PUN while_CJS not_XX0 evaluated_VVN during_PRP the_AT0 project_NN1 ,_PUN may_VM0 have_VHI been_VBN disadvantageous_AJ0 due_AV0 to_PRP the_AT0 high_AJ0 carbon_NN1 footprint_NN1 of_PRF additional_AJ0 enclosure_NN1 materials_NN2 ._SENT 
