Introduction

Human beings can remain healthy and active only with­in cer­tain bound­ed tem­per­a­ture ranges. Though indi­vid­u­als and cul­tures have his­tor­i­cal­ly been able to adapt to Earth’s wide cli­mat­ic vari­ety, there are lim­its to these adap­ta­tions, and know­able con­se­quences when those lim­its are exceed­ed. Expand­ing research on the caus­es, forms, and com­pli­ca­tions of ther­mal extremes in the Anthro­pocene era sup­ports a recog­ni­tion of extreme heat events as a clear and present dan­ger to human health and well-being. Extreme Heat: Hot Cities – Adapt­ing to a Hot­ter World, orga­nized by the Design for Risk and Recon­struc­tion Com­mit­tee (DfRR) of the Amer­i­can Insti­tute of Archi­tects New York, marks a con­ver­gence of dis­ci­plines that focus on heat waves as a health haz­ard, at both local and glob­al scales. As the program’s Novem­ber 2015 sym­po­sium under­scored, heat waves are increas­ing as the cli­mate changes, yet they are reme­di­a­ble through adjust­ments in the built envi­ron­ment and its asso­ci­at­ed social sys­tems.

The urban heat island effect exac­er­bates glob­al-scale ris­es in tem­per­a­ture, and local heat waves are increas­ing in both sever­i­ty and fre­quen­cy. Par­tic­u­lar­ly in urban hard­scape envi­ron­ments, where pop­u­la­tions face oth­er sources of vul­ner­a­bil­i­ty involv­ing access to cool­ing, mobil­i­ty, med­ical care, and social, cul­tur­al, and eco­nom­ic resources, heat waves have become an ear­ly and crit­i­cal front in the strug­gle against dele­te­ri­ous cli­mate-change effects. Archi­tects, plan­ners, engi­neers, pub­lic offi­cials, sci­en­tists, schol­ars, and the busi­ness sec­tor are accord­ing­ly devel­op­ing strate­gies that pur­sue the nonex­clu­sive aims of cli­mate adap­ta­tion and mit­i­ga­tion in urban set­tings. Togeth­er, these endeav­ors con­sti­tute a dis­tinct domain of knowl­edge and prac­tice: urban heat man­age­ment.

This field builds on best prac­tices that are already in place with­in healthy com­mu­ni­ties. Lead­ers in the archi­tec­tur­al, engi­neer­ing, and con­struc­tion (AEC) indus­tries rec­og­nize that a sta­ble com­mu­ni­ty engages a tri­ad of sus­tain­abil­i­ty: it is resilient social­ly, eco­nom­i­cal­ly, and eco­log­i­cal­ly. Some oth­er indus­tries have yet to accept these goals ful­ly, and AEC pro­fes­sion­als have a respon­si­bil­i­ty and oppor­tu­ni­ty to advo­cate for poli­cies that ele­vate the sus­tain­able stan­dards of the built envi­ron­ment. The ben­e­fits from these prac­tices are not lim­it­ed to improved tem­per­a­ture ranges in our cities; they extend to the entire plan­et.

Adaptive Mitigation

His­tor­i­cal­ly, there has been resis­tance to invest­ing in cli­mate change adap­ta­tion on the grounds that it would divert resources sup­port­ing mit­i­ga­tion. Adapt­ing to high­er glob­al tem­per­a­tures, some hold, would be a capit­u­la­tion to inter­ests that are impli­cat­ed in green­house gas emis­sions, or to a cyn­i­cal fatal­ism about humanity’s future, or both. How­ev­er, the experts that assem­bled at the Extreme Heat sym­po­sium reject the zero-sum assump­tion that the rela­tion between adap­ta­tion and mit­i­ga­tion is fun­da­men­tal­ly adver­sar­i­al. Instead, tak­ing a term from speak­er Bri­an Stone, the two inte­grate through adap­tive mit­i­ga­tion. This strat­e­gy rec­og­nizes that both com­po­nents are imper­a­tive and that action on both fronts can be mutu­al­ly rein­forc­ing.

As a strat­e­gy, adap­tive mit­i­ga­tion rec­og­nizes that cli­mate change adap­ta­tion and mit­i­ga­tion are both imper­a­tive and that action on both fronts can be mutu­al­ly rein­forc­ing.

Adap­tive mit­i­ga­tion com­pris­es many inter­ven­tions that advance mul­ti­ple aims. Such aims include refor­esta­tion and regreen­ing of urban envi­ron­ments (cool­ing local sites through evap­o­tran­spi­ra­tion and shad­ing while improv­ing car­bon bal­ance and air qual­i­ty), com­pact tran­sit-ori­ent­ed devel­op­ment (reduc­ing both auto­mo­tive green­house gas emis­sions and waste heat), and cov­er­age of heat-absorb­ing infra­struc­ture, such as park­ing lots, with pho­to­volta­ic pan­els (reduc­ing heat con­cen­tra­tion in asphalt by shad­ing while pro­vid­ing renew­able ener­gy). The design, engi­neer­ing, and plan­ning pro­fes­sions, sym­po­sium speak­ers con­tend, have the oppor­tu­ni­ty to gen­er­ate win-win sce­nar­ios that address these aims and ampli­fy incen­tives for their expan­sion.

Keith Hughes of Autodesk, a fittingly ardent advocate of robust tools and systems, introduces the “Urban Heat and Infrastructure” panel.

Kei­th Hugh­es of Autodesk, a fit­ting­ly ardent advo­cate of robust tools and sys­tems, intro­duces the “Urban Heat and Infra­struc­ture” pan­el.

Health Priorities and the Climate-Science Consensus

For urban dwellers, local heat waves bring glob­al-scale ris­es in tem­per­a­ture close to home, and they do not spare dis­be­liev­ers in such phe­nom­e­na. The hottest year in which glob­al tem­per­a­tures have ever been record­ed was 2015, accord­ing to Nation­al Ocean­ic and Atmos­pher­ic Admin­is­tra­tion (NOAA) data. With the excep­tion of 1998, a strong El Niño year like 2015 that is tied for sixth hottest, 15 of Earth’s 16 warmest years on record occurred in the 21st cen­tu­ry. Heat waves are not just incon­ve­nient but dead­ly, and their increas­ing haz­ards call for pur­pose­ful, sci­en­tif­i­cal­ly guid­ed action by all rel­e­vant pro­fes­sion­al sec­tors. Even skep­tics of the data can rec­og­nize the health risks asso­ci­at­ed with extreme heat, and acknowl­edge the impor­tance of engag­ing in adap­tive mit­i­ga­tion.

Expand­ed aware­ness of acute heat stroke and heat- exac­er­bat­ed chron­ic dis­or­ders is no longer the exclu­sive province of med­ical per­son­nel, but a mat­ter for design, engi­neer­ing, and plan­ning pro­fes­sion­als to con­sid­er in their cre­ation of healthy, sus­tain­able com­mu­ni­ties. Detailed stud­ies of indi­vid­ual heat waves and their geo­graph­ic vul­ner­a­bil­i­ty pat­terns shows cor­re­la­tions between the dis­tri­b­u­tion of com­mu­ni­ty resources and rates of mor­bid­i­ty and mor­tal­i­ty in heat-affect­ed neigh­bor­hoods. These cor­re­la­tions under­score the impor­tance of proac­tive­ly bol­ster­ing and restor­ing soci­etal safe­ty nets wher­ev­er they are in dis­re­pair. Human health cor­re­sponds with the built envi­ron­ment, and its pro­mo­tion is insep­a­ra­ble from envi­ron­men­tal jus­tice.

Human health cor­re­sponds with the built envi­ron­ment, and its pro­mo­tion is insep­a­ra­ble from envi­ron­men­tal jus­tice.

This cor­re­la­tion, often most tan­gi­bly expe­ri­enced through med­ical and human­i­tar­i­an frame­works in the con­text of heat island-relat­ed haz­ards, is not always enough to spur action. In order to over­ride polit­i­cal paral­y­sis and over­come dis­in­for­ma­tion in the mar­shal­ing of pub­lic per­cep­tions about cli­mate-relat­ed risks, we need to gath­er more data and share it more com­pelling­ly. The research to date points promis­ing­ly toward adap­tive and mit­i­gat­ing strate­gies that are achiev­able with known tech­nolo­gies. Oth­er mea­sures require fur­ther detailed data (e.g., on inter­me­di­ate-range cli­mate pro­jec­tions, the gran­u­lar ther­mal changes effect­ed by urban refor­esta­tion, or the rel­a­tive ben­e­fits of green and cool roofs in dif­fer­ent set­tings), and all com­men­ta­tors sup­port expan­sion and refine­ment of the knowl­edge base. View­ing health- ori­ent­ed data as an essen­tial sig­nal and cli­mate pol­i­tics as noise, one of the clear­est rec­om­men­da­tions through­out the sym­po­sium is the need for a high­er sig­nal-to-noise ratio in the grow­ing dis­course about cli­mate and heat.

View­ing health-ori­ent­ed data as an essen­tial sig­nal and cli­mate pol­i­tics as noise, one of the clear­est rec­om­men­da­tions through­out the sym­po­sium is the need for a high­er sig­nal-to-noise ratio.

Biomimetic and Neotechnic Design

Organ­isms have been able to adapt to hot eco­log­i­cal nich­es for much longer than humans have been deploy­ing mech­a­nisms toward sim­i­lar ends. Inspired by this abil­i­ty, many design pro­fes­sion­als study nature’s meth­ods of con­serv­ing and employ­ing water, using shade and cir­ca­di­an rhythms, man­ag­ing ener­gy trans­fer, and max­i­miz­ing the effi­cien­cy of forms. The result­ing bio­mimet­ic strate­gies char­ac­ter­ize many advanced build­ings and mate­ri­als, which are achiev­ing high ener­gy-con­ser­va­tion per­for­mance in even the hottest of sites. Of the AEC indus­tries’ bio­mimet­ic advance­ments, espe­cial­ly notable are: the attain­ment of net-zero ener­gy input/output bal­ance in both new con­struc­tion and retro­fits; the use of solar heat gain to (para­dox­i­cal­ly) cool a build­ing; the poten­tial of pho­to­volta­ic pan­els to pow­er con­den­sa­tion and irri­ga­tion sys­tems that then trans­form desert sites into agri­cul­tur­al pro­duc­tion cen­ters; and the role of select­ed plant species in assist­ing with gray­wa­ter treat­ment and ther­mal man­age­ment when inte­grat­ed into build­ing sys­tems.

Grimshaw Architects’ Andrew Whalley shares biomimicry’s influence on the firm’s design work. Photo by Samuel Lahoz.

Grimshaw Archi­tects’ Andrew Whal­ley shares biomimicry’s influ­ence on the firm’s design work.

Along­side the use of nat­ur­al mod­els and nat­ur­al build­ing com­po­nents, strate­gies for heat man­age­ment draw from the for­mal vocab­u­lar­ies of indige­nous archi­tec­tur­al tra­di­tions in hot regions. Aid­ed by con­tem­po­rary para­met­ric design tools, design pro­fes­sion­als are craft­ing site-spe­cif­ic forms that use pre­vail­ing winds and inter­nal air­flow pat­terns to pas­sive­ly aug­ment cool­ing. The era dom­i­nat­ed by sealed build­ing envelopes, per­va­sive imper­vi­ous hard­scapes, stan­dard­ized indus­tri­al mate­ri­als, and prof­li­gate use of fos­sil-fuel-pow­ered mechan­i­cal ven­ti­la­tion can and should end. Instead, we have the oppor­tu­ni­ty to embrace a range of time-test­ed and nature-test­ed sys­tems based on ther­mal mass, shad­ing, strate­gic light­ing, insu­la­tion, and hydrol­o­gy, all coor­di­nat­ed through sen­sors and infor­ma­tion tech­nol­o­gy. A more adap­tive approach to ther­mal con­trol can be a pow­er­ful dri­ver of the com­pre­hen­sive tran­si­tion from pale­otech­nics to neotech­nics, draw­ing on the most endur­ing strate­gies of eotech­nics (to bor­row the ter­mi­nol­o­gy of Lewis Mum­ford), in design, engi­neer­ing, and con­struc­tion.

1040_IMF_6481

NYC ORR’s Kizzy Charles-Guz­man out­lines some of the City’s meth­ods for address­ing resilience.

Complexity and Interdependencies

Extreme heat calls for sit­u­a­tion­al­ly-spe­cif­ic approach­es that are informed by both short- and long-term con­sid­er­a­tions, and that ful­ly weigh the nuanced impli­ca­tions of the approach. One conun­drum rec­og­nized by sev­er­al sym­po­sium speak­ers is that mechan­i­cal air con­di­tion­ing, the most imme­di­ate form of relief dur­ing an acute heat wave, also con­tributes to waste heat and ener­gy con­sump­tion. Out­side of the rare set­tings where renew­able ener­gy sources are dom­i­nant, mechan­i­cal air con­di­tion­ing also con­tributes to green­house gas emis­sions. Sim­i­lar­ly, green (veg­e­tat­ed), cool (white or sil­ver), and blue (water-cap­tur­ing) roofs may con­sti­tute low-hang­ing fruit for cities seek­ing cost-effec­tive ways to increase urban albe­do. How­ev­er, some pre­lim­i­nary obser­va­tions sug­gest that the result­ing tem­per­a­ture dif­fer­en­tials are con­ducive to under­side mois­ture con­den­sa­tion, or that the light reflect­ed off a roof may still result in a warmer atmos­phere, among oth­er con­cerns. Urban den­si­ty is often cit­ed as a pos­i­tive coun­ter­force against cli­mate change, since denser habi­tats ampli­fy effi­cien­cies in trans­porta­tion, win­ter heat­ing, and oth­er ener­gy-using, car­bon-gen­er­at­ing activ­i­ties. Yet urban envi­ron­ments max­i­mize vul­ner­a­bil­i­ty to heat haz­ards, as evi­denced in the 1995 Chica­go heat wave, the 2003 Euro­pean heat wave, the ther­mal aspects of Hur­ri­cane Kat­ri­na in 2005, and oth­er high-mor­tal­i­ty events. As New York City expe­ri­enced dur­ing Hur­ri­cane Sandy, inter­de­pen­dent infra­struc­ture sys­tems, such as elec­tri­cal grids and trans­porta­tion, can be very vul­ner­a­ble to cas­cades of fail­ure.

University of Wisconsin–Madison’s Richard Keller, author of Fatal Isolation: The Devastating Paris Heat Wave of 2003, shares his latest research. Photo by Samuel Lahoz.

Uni­ver­si­ty of Wisconsin–Madison’s Richard Keller, author of Fatal Iso­la­tion: The Dev­as­tat­ing Paris Heat Wave of 2003, shares his lat­est research.

These illus­tra­tions of com­plex­i­ty and inter­de­pen­den­cy imply that tru­ly inter­dis­ci­pli­nary work has crit­i­cal, con­crete val­ue in this field. That so many sym­po­sium par­tic­i­pants call for col­lab­o­ra­tion among pro­fes­sions is nei­ther an acci­dent nor an automa­tism, but a pur­pose­ful col­lec­tive recog­ni­tion that heat man­age­ment is not a cat­e­go­ry of prob­lem for which any sin­gle mag­ic-bul­let solu­tion can suf­fice.

Incrementalism and Catastrophes

The “frog in boil­ing water” sto­ry, famous­ly recount­ed by Al Gore in An Incon­ve­nient Truth, con­tin­ues to have impor­tant metaphor­ic pow­er. While her­petol­o­gists have point­ed out that frogs do not actu­al­ly remain in water as it warms, the sto­ry poignant­ly con­veys the dif­fer­ent respons­es evoked by a grad­ual change and a sud­den shock. In the con­text of the cur­rent state of urban heat man­age­ment, these respons­es man­i­fest as abstract recog­ni­tion of haz­ards requir­ing an even­tu­al response and shock-hard­ened actions that are imme­di­ate, dras­tic, and dis­rup­tive.

Prepa­ra­tion and resilience, as artic­u­lat­ed by the sym­po­sium speak­ers and reg­u­lar­ly by DfRR lead­er­ship, call for a steady accel­er­a­tion in these con­cep­tu­al nego­ti­a­tions between grad­ual and emer­gency respons­es. Urban cat­a­stro­phes such as Hur­ri­cane Sandy reveal the weak­ness­es in infra­struc­tur­al and social sys­tems, while gen­er­at­ing (if only momen­tar­i­ly) pub­lic and polit­i­cal sup­port for invest­ments that pre­vent or mit­i­gate a recur­rence of sim­i­lar events. It is essen­tial to rein­force and extend these peri­ods of recog­ni­tion and res­o­lu­tion beyond the imme­di­ate after­math of a cat­a­stro­phe, so that pub­lic atten­tion does not erode and the polit­i­cal will to mar­shal resources con­struc­tive­ly is pre­served.

It is essen­tial to extend these peri­ods of recog­ni­tion and res­o­lu­tion beyond the imme­di­ate after­math of a cat­a­stro­phe.

Heat as Potential Asset

There may be an opti­mistic way of view­ing the immense amount of excess heat in today’s urban envi­ron­ments, as empha­sized by Anna Dyson and Chris Bene­dict, among oth­er sym­po­sium speak­ers. By rec­og­niz­ing heat as a form of ener­gy that can be redi­rect­ed rather than wast­ed, a range of heat-recap­ture tech­nolo­gies offers the pos­si­bil­i­ty of improv­ing on cur­rent­ly dom­i­nant ener­gy tech­nolo­gies in both per­for­mance and sus­tain­abil­i­ty. Such tech­nolo­gies can be found in the ener­gy-recov­ery ven­ti­la­tors of Pas­sive House build­ings, in the recir­cu­lat­ing sys­tems of inte­grat­ed cap­il­lary-tube façade pan­els, and in high-effi­cien­cy solar heat col­lec­tors.

The ben­e­fits of heat-con­scious design at the sin­gle-build­ing scale will aggre­gate, impact­ing neigh­bor­hood, munic­i­pal, and region­al scales.

As advances in mate­r­i­al sci­ence and green chem­istry enable greater ther­mal effi­cien­cy on the sin­gle-build­ing scale, the ben­e­fits of heat-con­scious design will aggre­gate to impact neigh­bor­hood, munic­i­pal, and region­al scales, and beyond. To suc­cess­ful­ly make heat an asset in a sin­gle build­ing project is to move us one step clos­er to har­ness­ing heat’s pos­i­tive impacts glob­al­ly. In addi­tion to embrac­ing the urgency of haz­ard reme­di­a­tion, urban heat man­age­ment involves rec­og­niz­ing long-range oppor­tu­ni­ties to re-engi­neer the built envi­ron­ment in ways that con­serve, apply, and hon­or the gifts of the sun and the Earth.

Architecture & Energy Limited principal Chris Benedict offers insights about Passivhaus building design.

Archi­tec­ture & Ener­gy Lim­it­ed prin­ci­pal Chris Bene­dict offers insights about Pas­sivhaus build­ing design.

Implications for Advocacy and Action

Extreme heat events are becom­ing more fre­quent, mak­ing it crit­i­cal for archi­tects, plan­ners, engi­neers, pub­lic offi­cials, sci­en­tists, schol­ars, and the busi­ness sec­tor to mobi­lize. The vari­eties of evi­dence and dis­course offered at this sym­po­sium point to the fol­low­ing forms of action:

Design should sup­port the capac­i­ty of a build­ing or infra­struc­tur­al project to man­age crit­i­cal resources (ther­mal and elec­tri­cal ener­gy, air, water, infor­ma­tion) more effi­cient­ly and in ways more con­ducive to health. Design should draw from the full range of avail­able strate­gies, from traditional/vernacular forms that use shad­ing, ori­en­ta­tion, pas­sive ven­ti­la­tion, and ther­mal mass­ing, to more con­tem­po­rary tech­nolo­gies and mate­ri­als, such as pho­to­voltaics, hydro­log­ic inno­va­tions, green chem­istry, waste-heat recovery/reuse and oth­er Pas­sive House tech­niques, and biophilic/biomimetic prin­ci­ples. In this are­na, archi­tects have the oppor­tu­ni­ty to take lead­er­ship roles both in pre­lim­i­nary design phas­es and in post-occu­pan­cy phas­es.

Build­ing codes should enforce and encour­age sus­tain­able, resilient, and ther­mal­ly pro­tec­tive stan­dards. Spe­cif­ic areas to be addressed include ener­gy man­age­ment (includ­ing renew­able sourc­ing and net-zero ener­gy input/output bal­anc­ing), cool roofs, cool pave­ments, veg­e­ta­tive canopy cov­er and oth­er shad­ing strate­gies, access to ener­gy-effi­cient air con­di­tion­ing, air qual­i­ty, max­i­mum indoor tem­per­a­tures, gray­wa­ter reuse, and oth­er ther­mal­ly rel­e­vant vari­ables. Changes in code
should incor­po­rate best prac­tices based on the most reli­able con­tem­po­rary research and incen­tivize con­tin­ued research and ele­va­tion of stan­dards.

Poli­cies at the com­mu­ni­ty, region­al, and nation­al scales should fos­ter steady-state sus­tain­abil­i­ty, mit­i­ga­tion of heat island effect, and acute event resilience in social, eco­nom­ic, and envi­ron­men­tal man­ners. Top pri­or­i­ty top­ics include: access to emer­gency cool­ing cen­ters, med­ical pre­pared­ness, pub­lic edu­ca­tion and out­reach about heat-relat­ed haz­ards; appro­pri­ate urban den­si­fi­ca­tion; ener­gy-effi­cient trans­porta­tion, nat­ur­al dis­as­ter or black­out prepa­ra­tion and response, inter-agency and inter-city coor­di­na­tion, social cohe­sion, behavioral/cultural adap­ta­tions, equi­table ser­vices and atten­tion to the needs of high­ly vul­ner­a­ble pop­u­la­tions, refor­esta­tion and urban regreen­ing, ecosys­tem restora­tion, and region­al­ly spe­cif­ic bio­di­ver­si­ty man­age­ment. Pol­i­cy should also encour­age and enforce ongo­ing research into the ther­mal, pub­lic health, and cli­mat­ic effects of all rel­e­vant prac­tices by the AEC indus­tries, pub­lic and pri­vate enti­ties respon­si­ble for infra­struc­ture, and oth­er social sec­tors.