Saurin gudun zafi ta cikin abu ko taro

U-value yana auna yawan zafin da ke wucewa ta wani ɓangaren gini a kowane yanki, a kowane bambancin zafin jiki. Ana auna shi a W/(m²·K) ko BTU/(h·ft²·°F). Ƙananan U-value = rufi mafi kyau. Tagogi, bango, da rufi duk suna da kimar U-value.

Misali: Taga mai U=0.30 W/(m²·K) tana rasa watts 30 a kowane murabba'in mita ga kowane 1°C bambancin zafin jiki. U=0.20 yana da 33% mafi kyawun rufi.

Ikon abu don tsayayya wa gudun zafi

R-value shine juyin U-value (R = 1/U). Babban R-value = rufi mafi kyau. Ana auna shi a m²·K/W (SI) ko ft²·°F·h/BTU (US). Dokokin gini suna ƙayyade mafi ƙarancin R-values ga bango, rufi, da bene dangane da yankunan yanayi.

Misali: R-19 fiberglass batt yana ba da juriya 19 ft²·°F·h/BTU. R-38 a cikin soro ya ninka R-19 tasiri sau biyu.

Halayen abu: yadda yake johtar da zafi

Johtarwar zafi (λ ko k) wani hali ne na cikin abu da ake auna shi a W/(m·K). Ƙananan k-value = mai rufi mai kyau (foam, fiberglass). Babban k-value = mai johtarwa mai kyau (jan ƙarfe, aluminum). Ana amfani da shi don lissafin R-value: R = kauri / k.

Misali: Fiberglass k=0.04 W/(m·K), karfe k=50 W/(m·K). Karfe yana johtar da zafi sau 1250 fiye da fiberglass!

Lambobi mafi girma = rufi mafi kyau

R-value yana da sauƙin fahimta: R-30 ya fi R-15. Ana amfani da shi a Arewacin Amurka don samfuran rufi. Ana tara darajoji a jere: yadudduka suna taruwa. Yana da yawa a cikin gine-ginen zama, dokokin gini, da lakabin samfur.

• Raka'o'i: ft²·°F·h/BTU (US) ko m²·K/W (SI)
• Matsayi: R-3 (taga mai gilashi ɗaya) zuwa R-60 (rufin soro)
• Misalin bango: rami R-13 + foam R-5 = jimlar R-18
• Dokar babban yatsa: R-value a kowane inci ya bambanta da abu (R-3.5/inci don fiberglass)
• Manufofi na yau da kullun: bango R-13 zuwa R-21, rufi R-38 zuwa R-60
• Talla: Ana tallata samfura ta hanyar R-value ('R-19 batts')

Lambobi mafi ƙanƙanta = rufi mafi kyau

U-value ba shi da sauƙin fahimta: U-0.20 ya fi U-0.40. Ana amfani da shi a duniya, musamman don tagogi da lissafin gine-gine gaba ɗaya. Ba ya taruwa a sauƙaƙe—yana buƙatar lissafin juyawa. Yana da yawa a cikin gine-ginen kasuwanci da dokokin makamashi.

• Raka'o'i: W/(m²·K) ko BTU/(h·ft²·°F)
• Matsayi: U-0.10 (taga mai gilashi uku) zuwa U-5.0 (taga mai gilashi ɗaya)
• Misalin taga: U-0.30 yana da babban aiki, U-0.20 gida ne mai wucewa
• Lissafi: Asarar zafi = U × Yanki × ΔT
• Manufofi na yau da kullun: tagogi U-0.30, bango U-0.20 (kasuwanci)
• Matsayin: ASHRAE, IECC suna amfani da U-values don tsara makamashi

Gudun zafi ta cikin kayan aiki masu ƙarfi

Zafi yana canja wuri ta hanyar haɗuwa kai tsaye tsakanin kwayoyin halitta. Karfe suna johtar da zafi da sauri, yayin da kayan rufi suke tsayayya. Ana sarrafa shi ta Dokar Fourier: q = k·A·ΔT/d. Yana da rinjaye a cikin bango, rufi, bene.

• Sandunan karfe suna haifar da gadarorin zafi (karuwar asarar zafi da 25%)
• Hannun kwanon soya mai zafi yana johtar da zafi daga murhu
• Gudun zafi ta bango daga ciki mai dumi zuwa waje mai sanyi
• Rufi yana rage canja wurin zafi ta hanyar johtarwa

Canja wurin zafi ta hanyar motsin ruwa/iska

Zafi yana motsawa tare da gudun iska ko ruwa. Convection na halitta (iska mai dumi tana tashi) da convection mai tilastawa (masu busa, iska). Saduwar iska tana haifar da babban asarar zafi. Rufe iska yana dakatar da convection; rufi yana dakatar da johtarwa.

• Iska mai shiga ta ramuka da tsagewa (infiltration/exfiltration)
• Iska mai dumi tana fita ta soro (tasirin bututu)
• Rarraba zafi/sanyi da aka tilasta
• Iska tana ƙara asarar zafi ta bango

Canja wurin zafi ta hanyar taguwar lantarki

Duk abubuwa suna fitar da radiation na zafi. Abubuwa masu zafi suna fitar da ƙarin. Ba ya buƙatar haɗuwa ko iska. Katangar radiation (takarda mai haske) tana toshe 90%+ na zafin radiation. Babban dalili a soraye da tagogi.

• Hasken rana yana dumama ta tagogi (samun rana)
• Katangar radiation a soro tana nuna zafi
• Murfin taga mai ƙarancin fitarwa yana rage zafin radiation
• Zafin infrared daga rufin zafi yana haskakawa zuwa bene na soro

Masu gida da magina suna amfani da R-values da U-values a kullum:

• Zaɓin rufi: farashi/fa'idar R-19 vs R-21 batt na bango
• Sauya taga: taga mai gilashi uku U-0.30 vs taga mai gilashi biyu U-0.50
• Binciken makamashi: hoton zafi yana gano ramukan R-value
• Bin doka: cika mafi ƙarancin R-values na gida
• Shirin sake gyarawa: ƙara R-30 zuwa soro na R-19 (raguwar asarar zafi da 58%)
• Rage kuɗi na amfani: da yawa suna buƙatar mafi ƙarancin R-38 don ƙarfafawa

U-values ne ke ƙayyade nauyin dumama da sanyaya:

• Lissafin asarar zafi: Q = U × A × ΔT (Manual J)
• Girma na kayan aiki: rufi mafi kyau = ana buƙatar ƙaramin na'urar HVAC
• Tsarin makamashi: BEopt, EnergyPlus suna amfani da U-values
• Rufin bututu: mafi ƙarancin R-6 a wuraren da ba a daidaita su ba
• Nazarin biyan kuɗi: lissafin ROI na haɓaka rufi
• Jin daɗi: ƙananan U-values suna rage tasirin bango/taga mai sanyi

Manyan gine-gine suna buƙatar ingantattun lissafin zafi:

• Bin ASHRAE 90.1: teburan U-value da aka tsara
• Takardar shaidar LEED: wuce doka da 10-40%
• Tsarin bango na labule: taro na U-0.25 zuwa U-0.30
• Adanar sanyi: bango na R-30 zuwa R-40, rufi na R-50
• Nazarin farashin makamashi: $100K+ tanadi na shekara-shekara daga mafi kyawun ambulaf
• Binciken gadar zafi: nazarin haɗin karfe da FEA

Gine-gine masu inganci sosai suna tura iyakokin aikin zafi:

• Tagogi: U-0.14 zuwa U-0.18 (gilashi uku, cike da krypton)
• Bango: R-40 zuwa R-60 (inci 12+ na foam ko cellulose mai yawa)
• Tushe: R-20 zuwa R-30 rufi mai ci gaba na waje
• Rufewar iska: 0.6 ACH50 ko ƙasa (raguwa da 99% vs daidaitaccen)
• Mai iska mai dawo da zafi: ingancin 90%+
• Jimla: raguwar dumama/sanyaya da 80-90% vs mafi ƙarancin doka

• Rufe iska da farko: saka hannun jari na $500, tanadin makamashi 20% (mafi kyawun ROI fiye da rufi)
• Rufin soro: R-19 zuwa R-38 yana biya kansa a cikin shekaru 3-5
• Sauya taga: tagogin U-0.30 suna rage asarar zafi da 40% idan aka kwatanta da U-0.50
• Rufin bene na ƙasa: R-10 yana adana 10-15% na kuɗin dumama
• Sauya ƙofa: ƙofar karfe mai rufi (U-0.15) vs ƙofar katako mara komai (U-0.50)

• Kyamarar infrared: tana nuna rufin da ya ɓace da saduwar iska
• Gwajin ƙofar busa: yana auna yawan saduwar iska (ma'aunin ACH50)
• Gwajin taɓawa: bango/rufi masu sanyi suna nuna ƙarancin R-value
• Tarin kankara: alamar rashin isasshen rufin soro (zafi yana narkar da dusar ƙanƙara)
• Ruwan sanyi: yana nuna gadar zafi ko saduwar iska

• Yanayi mai sanyi: haɓaka R-value, rage U-value (fifikon rufi)
• Yanayi mai zafi: katangar radiation a soro, tagogin Low-E suna toshe samun rana
• Yanayi mai gauraye: daidaita rufi da inuwa da iska
• Yanayi mai laima: katangar tururi a gefen dumi, hana ruwan sanyi
• Yanayi mai bushewa: mayar da hankali kan rufe iska (tasiri mafi girma fiye da yankuna masu laima)

• Mafi kyawun ROI: Rufe iska (20:1), rufin soro (5:1), rufe bututu (4:1)
• Matsakaicin ROI: Rufin bango (3:1), rufin bene na ƙasa (3:1)
• Na dogon lokaci: Sauya taga (2:1 a cikin shekaru 15-20)
• Yi la'akari: rage kuɗi na amfani na iya inganta ROI da 20-50%
• Biyan kuɗi: Biyan kuɗi mai sauƙi = farashi / tanadi na shekara-shekara

Igloos suna kiyaye 4-16°C a ciki lokacin da yake -40°C a waje ta amfani da dusar ƙanƙara da aka matse (R-1 a kowane inci). Siffar dome tana rage yanki, kuma ƙaramin ramin shiga yana toshe iska. Aljihunan iska a cikin dusar ƙanƙara suna ba da rufi—tabbacin cewa iska da aka kama shine sirrin duk rufi.

Tiles na zafin jirgin sama suna da ƙarancin johtarwar zafi (k=0.05) wanda za su iya zama ~1100°C a gefe ɗaya kuma a iya taɓa su a ɗayan. An yi su da 90% silica cike da iska, su ne mafi kyawun kayan rufi—R-50+ a kowane inci a yanayin zafi mai yawa.

Gidajen da aka gina kafin 1940s galibi ba su da rufin bango—kawai gefen katako, sanduna, da filasta (jimlar R-4). Ƙara rufin R-13 zuwa R-19 yana rage asarar zafi da 70-80%. Yawancin tsofaffin gidaje suna rasa zafi da yawa ta bango fiye da ta soro da ba a rufe su da kyau ba.

Kankara tana da k=2.2 W/(m·K), gilashi yana da k=1.0. Amma iska (k=0.026) da aka kama a cikin lu'ulu'un kankara ya sa dusar ƙanƙara/kankara ta zama rufi mai kyau. Abin mamaki, dusar ƙanƙara mai laima a kan rufi ta fi rufi (R-1.5/inci) fiye da kankara mai ƙarfi (R-0.5/inci) saboda aljihunan iska.

Fiberglass batt da aka ƙididdige R-19 (inci 5.5) da aka matse zuwa inci 3.5 yana rasa 45% na R-value ɗinsa (ya zama R-10). Aljihunan iska—ba zaren ba—suna ba da rufi. Kada a taɓa matse rufi; idan bai dace ba, yi amfani da abu mai yawa.

Aerogel shine 99.8% iska kuma yana riƙe da Guinness Records 15 don rufi. A R-10 a kowane inci (vs R-3.5 don fiberglass), shine rufin da NASA ta fi so. Amma farashi ($20-40/sq ft) ya iyakance shi ga aikace-aikace na musamman kamar na'urorin Mars da barguna na rufi masu sirara.

R-value yana auna juriya ga gudun zafi (mafi girma = rufi mafi kyau). U-value yana auna saurin watsa zafi (mafi ƙanƙanta = rufi mafi kyau). Suna da dangantakar juyawa a lissafi: U = 1/R. Misali: rufin R-20 = U-0.05. Yi amfani da R-value don samfuran rufi, U-value don tagogi da lissafin taro gaba ɗaya.

Ee, amma tare da raguwar dawowa. Daga R-0 zuwa R-19 yana rage asarar zafi da 95%. Daga R-19 zuwa R-38 yana rage wani 50%. Daga R-38 zuwa R-57 yana rage 33% kawai. Da farko, rufe iska (tasiri mafi girma fiye da rufi). Sannan ƙara rufi inda R-value ya fi ƙanƙanta (yawanci soro). Bincika rufin da aka matse ko ya jike—sauyawa ya fi ƙarawa.

Al'ada da rikitarwa. Tagogi suna da hanyoyin canja wurin zafi da yawa (johtarwa ta gilashi, radiation, convection a cikin ramukan iska) wanda ya sa U-value ya fi dacewa don ƙididdigar aiki gaba ɗaya. Bango sun fi sauƙi—mafi yawanci johtarwa—don haka R-value yana da sauƙin fahimta. Duk ma'auni suna aiki ga kowane; kawai fifikon masana'antu ne.

Tabbas! R-value yana tsayayya wa gudun zafi a dukkan kwatance. A lokacin rani, rufin soro na R-30 yana kiyaye zafi a WAJE kamar yadda yake kiyaye zafi a CIKI a lokacin sanyi. Yanayi mai zafi yana amfana daga babban R-value + katangar radiation + rufi masu launin haske. Mayar da hankali kan soro (mafi ƙarancin R-38) da bango da ke fuskantar yamma.

Rufe iska da farko, sannan rufi. Saduwar iska na iya wucewa ta rufi gaba ɗaya, yana rage R-30 zuwa R-10 mai tasiri. Nazari ya nuna cewa rufe iska yana ba da ROI sau 2-3 fiye da rufi kawai. Rufe da farko (caulk, weatherstripping, foam), sannan rufe. Tare suna rage amfani da makamashi da 30-50%.

Raba 1 da R-value: U = 1/R. Misali: bango R-20 = 1/20 = U-0.05 ko 0.28 W/(m²·K). Juyawa: R = 1/U. Misali: taga U-0.30 = 1/0.30 = R-3.3. Lura: raka'o'i suna da mahimmanci! R-values na Amurka suna buƙatar abubuwan canji don SI U-values (ninka da 5.678 don samun W/(m²·K)).

Karfe yana da johtarwa sau 1250 fiye da rufi. Sandunan karfe suna haifar da gadarorin zafi—hanyoyin johtarwa kai tsaye ta cikin taron bango. Bango mai rufin rami na R-19 da sandunan karfe yana samun R-7 mai tasiri kawai (raguwa da 64%!). Magani: rufi mai ci gaba (allon kumfa) a kan sanduna, ko firame na katako + kumfa na waje.

Ya dogara da yankin yanayi (1-8) da ɓangaren gini. Misali: Yanki 5 (Chicago) yana buƙatar bango na R-20, rufin R-49, bene na ƙasa R-10. Yanki 3 (Atlanta) yana buƙatar bango na R-13, rufin R-30. Bincika dokar gini na gida ko teburan IECC. Yawancin hukunce-hukunce yanzu suna buƙatar bango na R-20+ da soro na R-40+ har ma a yanayi mai matsakaici.