Awnings: a simple cooling tech we apparently forgot about

Technology Connections

AI-assisted summary of Awnings: a simple cooling tech we apparently forgot about — original source. Check the original for full context.

Source published: 2024-07-15

Key ideas

Energy modeling on a standard Chicago home demonstrates that adding external window overhangs cuts annual cooling energy demand by 20% by blocking solar insolation before it strikes the glass. (7:56)
While static low-SHGC window glass reduces summer cooling needs, it creates a severe winter heating penalty in colder climates by permanently blocking free passive solar heat gain. (7:56)
Interior blinds and drapes fail to stop radiant heat gain because the energy has already breached the building envelope, absorbing into surfaces and driving interior temperatures up via the greenhouse effect. (13:31)
Homeowners Associations (HOAs) represent the single largest administrative hurdle to modern awning adoption, prompting calls for legislative protections similar to solar panel access laws. (19:25)

Detailed notes

## Background This video was published on YouTube by the channel Technology Connections on July 15, 2024. In the video description, the host playfully questions where window awnings disappeared to and links to his social media profiles and Patreon page.

## TL;DR The video examines how window awnings transitioned from essential passive cooling features in early twentieth-century architecture to an obsolete design trend stigmatized by mid-century real estate markets and supplanted by residential air conditioning. Drawing on building energy simulations and solar geometry, the host demonstrates that exterior awnings can slash annual cooling loads by roughly 20% without incurring the winter heating penalties tied to static low-SHGC window glass. While noting trade-offs such as dimming natural daylight, insect nesting, and maintenance, the presentation contrasts awnings favorably against interior blinds and European roller shutters. Ultimately, the video calls for dedicated academic research into awning performance and legislative reforms to prevent suburban HOAs from banning exterior shading retrofits.

## Atmosphere & style The video carries an earnest, conversational, and subtly wry tone driven by Alec's signature blend of consumer advocacy, physics-based reasoning, and retro enthusiasm. It feels like an engaging living room lecture where genuine technical irritation at inefficient modern construction practices is balanced with dry humor and cozy historical nostalgia. The pacing moves smoothly from vintage catalog appreciation into rigorous thermal energy debates, wrapping up with self-deprecating outtakes that puncture any lingering academic pretension.

## Bulletin - [07:56](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=476s) Energy modeling on a standard Chicago home demonstrates that adding external window overhangs cuts annual cooling energy demand by 20% by blocking solar insolation before it strikes the glass. - [07:56](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=476s) While static low-SHGC window glass reduces summer cooling needs, it creates a severe winter heating penalty in colder climates by permanently blocking free passive solar heat gain. - [13:31](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=811s) Interior blinds and drapes fail to stop radiant heat gain because the energy has already breached the building envelope, absorbing into surfaces and driving interior temperatures up via the greenhouse effect. - [19:25](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1165s) Homeowners Associations (HOAs) represent the single largest administrative hurdle to modern awning adoption, prompting calls for legislative protections similar to solar panel access laws.

## Key takeaways - [00:00](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=0s) Solar insolation triggers a greenhouse effect inside homes as radiant light passes through window glass and is re-emitted into living spaces as heat. - [02:34](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=154s) Historic architecture utilized deep porches, galleries, and exterior awnings to block direct solar radiation from touching window panes. - [06:17](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=377s) Residential air conditioning and mid-century aesthetic trends caused awnings to fall out of favor, stigmatizing them as indicators of homes lacking mechanical AC. - [07:56](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=476s) Adding window overhangs reduced annual cooling energy by 20% in an energy simulation of a Chicago single-family home. - [07:56](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=476s) Low-SHGC window glass penalizes northern homes in winter by permanently rejecting passive solar heat, whereas awnings exploit seasonal solar geometry to admit low winter sun. - [11:11](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=671s) Retrofitting high-SHGC windows with exterior awnings offers the same seasonal efficiency benefits as complex, custom-engineered architectural overhangs at a fraction of the cost. - [11:11](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=671s) In desert climates like Phoenix, five unshaded west-facing windows admit over a kilowatt of heat continuously on summer afternoons even with high-performance low-e glass. - [13:31](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=811s) Interior window coverings cannot match exterior shading because radiant energy has already crossed the building envelope and converted into heat inside the room. - [13:31](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=811s) Independent academic and building-code research quantifying the real-world efficiency of exterior window awnings remains surprisingly scarce. - [15:14](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=914s) Modern automated roller awnings can address historical maintenance downsides by retracting during high winds, overcast skies, or winter months. - [17:23](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1043s) Unlike European roller shutters that trap hot air pockets against the glazing and block visibility, open awnings allow natural convective airflow while preserving ground-level outdoor views. - [17:23](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1043s) Real-world thermal testing revealed a home gained twice as much indoor heat on clear sunny days compared to overcast days at identical ambient temperatures. - [19:25](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1165s) Suburban HOA architectural rules frequently prevent homeowners from installing exterior awnings, highlighting the need for statutory protections.

## Detailed walkthrough ### [00:00](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=0s) The Forgotten Art of Window Awnings and Insolation

There are certain architectural details from the not-too-distant past that seem blindingly obvious in retrospect, yet have strangely fallen out of favor. Window awnings—once a staple of cute brick ranches and neighborhood homes everywhere—are chief among them. While they have largely vanished from contemporary building trends, there is a compelling case to be made for reviving them. They are not being pitched here as part of an affiliate deal or brand endorsement, but rather as a neglected piece of practical technology. As the host points out, our ancestors cracked the code on keeping buildings comfortable, but modern society somehow decided it was too cool for awnings, which is deeply ironic considering keeping things cool is their primary objective.

```mermaid flowchart TD accTitle: Solar Insolation Mechanism in Homes accDescr: Sunlight passes through window glass, is absorbed by indoor surfaces, and re-radiates as trapped heat.

subgraph SunEnergy["Solar Radiation"] S["Sunlight / Solar Irradiance"] end

subgraph Interior["Indoor Living Space"] W["Window Glass"] F["Flooring & Furniture"] H["Heat Energy (Longwave IR)"] end

While people love windows for admitting natural daylight and providing views of the outdoors, they remain massive structural openings plugged with comparatively thin sheets of glass. Modern glass assemblies have dramatically improved thermal performance, but they still lag far behind the thick insulated walls that enclose them. The core issue is solar irradiance: when direct sunlight penetrates a transparent pane into an enclosed space, it triggers the greenhouse effect. Radiant light energy strikes interior flooring and furniture, which absorb the radiation and re-emit it into the living space as heat.

In the architecture and building science fields, this phenomenon of solar heat gain is known as *insolation* (distinct from thermal *insulation*). While modern low-emissivity glass coatings reflect a notable portion of this radiant energy, the sun is so overwhelmingly powerful that substantial heat still enters the building—a fact readily confirmed by any household cat seeking out a sunny floorboard. While welcome during freezing winter afternoons, this solar heating penalty is miserable during peak summer.

[02:34](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=154s) Ancestral Architecture and the Rise of the Awning in the 1920s

Historic builders recognized that the simplest way to defeat solar heat gain was to stop sunlight from ever touching the glass. If a structure is designed so its windows remain in full shade, the greenhouse effect cannot occur, keeping the living quarters noticeably cooler. This logic drove the construction of expansive covered porches across the American South and deep architectural galleries on historic French Quarter buildings in New Orleans. While deep porches and galleries doubled as rain shelters and comfortable outdoor living spaces, their primary thermal function was keeping the building envelope shaded even while the structure sat under direct midday sun.

To achieve that same shade without building an expensive, material-heavy wraparound porch, manufacturers popularized fabric and metal window awnings. Awnings surged into mainstream residential fashion in the 1920s, celebrated in trade journals and home magazines alike. An article in the 1927 issue of *Building Age and National Builder* made an unabashed aesthetic and functional argument: “A Beautiful home which is devoid of awnings resembles a well dressed man without a necktie. The awnings give that finishing touch, just the last point to complete the proper taste.”

Beyond styling, period literature focused heavily on thermal comfort and interior preservation. The 1927 article noted that shading porch spaces dropped the indoor temperature of adjoining rooms, adding: “The fact that the awning excludes the sun from the window glass is quite an important asset in reducing the temperature of the room, and in preventing the fading of wall paper and carpet.” In 1925, writers Hal and Helen Davis declared in *Better Homes and Gardens*: “Awnings - they have such possibilities, such delightful possibilities, that foolish indeed is a house to go without them, if they can be afforded.” They were framed as major real estate selling points, with diverse catalog options ranging from regional configurations to flamboyant spear-mounted "Arabian Awnings." A quick digital stroll through older Chicago neighborhoods via Google Street View proves how widespread they were, with many vintage homes still retaining south- and west-facing awnings that cast deep shadows over the glass during scorching afternoons while allowing windows to stay open during summer downpours.

[06:17](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=377s) How Air Conditioning and Fashion Killed the Awning

The almost total disappearance of window awnings from modern public consciousness came down to two powerful forces: mechanical air conditioning and cyclical fashion trends. Before residential air conditioning, passive cooling techniques were vital for survival and basic comfort. Once motorized, energy-intensive compressors were tied to the electrical grid, interior climates could be brute-forced to whatever temperature the homeowner desired. So long as an air conditioner was sized with enough raw cooling capacity to overpower the continuous solar heat gain through the windows, exterior shading ceased to be strictly necessary.

Within a few decades, postwar home construction abandoned exterior awnings entirely under the assumption that mechanical HVAC equipment could simply pump the excess heat back outside. As new homes were built with bare, unshaded facades, existing homes with awnings suddenly appeared dated. In the design and real estate worlds, looking dated was treated as a fatal defect. By the 1960s, exterior window awnings had transformed from a symbol of refined taste into an architectural telltale that a house lacked modern central air conditioning. Realtors began advising sellers to tear them down, declaring that no modern buyer wanted a home with awnings because they were associated with old fuddy-duddies and lower-income households. Outside of niche infomercials for retractable patio covers, window awnings faded into obscurity.

- Mechanical cooling substituted electrical grid energy for passive architectural shading. - Postwar tract homes dropped awnings to cut construction costs and celebrate modern aesthetic minimalism. - Mid-century real estate agents actively stigmatized awnings as indicators of an un-air-conditioned, low-income home.

[07:56](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=476s) Modern Modeling: Energy Savings vs. Low-E Window Tradeoffs

Bringing window awnings back makes practical and financial sense. Apart from offering architectural character and customizable personal flair, they relieve strain on power grids during brutal heatwaves and directly cut electricity consumption. To quantify these savings, an energy model was run on a typical Chicago single-family home to calculate annual heating and cooling loads under varying architectural conditions. The results revealed an immediate, dramatic benefit: “Doing nothing to the house but adding window overhangs reduced the annual cooling energy needed by 20%.”

```mermaid flowchart LR accTitle: Tradeoffs of Low SHGC Windows vs Seasonal Shading accDescr: Low SHGC glass reduces summer cooling demand but penalizes winter heating demand, whereas overhangs block high summer sun while admitting low winter sun.

subgraph LowSHGC["Low SHGC Glass Only"] C1["Summer Cooling Demand: -20%"] H1["Winter Heating Demand: +Significant Penalty"] Net1["Net Efficiency: Mixed in cold climates"] end

subgraph Overhangs["External Overhangs / Awnings"] C2["Summer Cooling Demand: -20%"] H2["High summer sun blocked"] H3["Low winter sun enters freely"] Net2["Net Efficiency: Optimal year-round"] end ```

However, evaluating whole-home energy demand requires understanding the nuanced tradeoffs of window technology. Modern high-performance "Low-E" glass is rated using the Solar Heat Gain Coefficient (SHGC), which measures the fraction of solar radiation admitted through a window assembly. In hot Southern climates where heating demand is virtually nonexistent, installing windows with an extremely low SHGC—blocking over 75% of solar heat gain—is an unqualified win.

In Northern climates like Chicago, static low-SHGC glass introduces a severe seasonal penalty: - Over the course of a full calendar year, northern homes consume far more energy for heating than for cooling. - In the computer simulation, swapping south-facing windows to a low-SHGC glass reduced summer cooling demand by an amount comparable to installing exterior overhangs. - That same low-SHGC glass caused winter heating demand to spike dramatically by permanently blocking free passive solar heat gain when outdoor temperatures plunged. - Fixed glass coatings cannot adapt between July and January, whereas exterior overhangs naturally take advantage of solar geometry—blocking the high summer sun while allowing low-angle winter sunlight to pass beneath the shade and warm the interior for free.

[11:11](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=671s) The Elegance of Awnings vs. Complex Architecture

The beauty of window awnings lies in resolving a fundamental architectural trade-off: homeowners do not have to choose between summer shading and winter heating performance. Instead of sacrificing cold-weather passive solar gains by installing windows with low solar heat gain coefficients (SHGC), one can install high-SHGC windows to harvest free thermal energy during the winter, and simply rely on an awning to shade the glass when the summer sun sits higher in the sky. While high-end custom home design sometimes achieves this by engineering permanent structural overhangs over specific window elevations and using low-gain windows elsewhere, retrofitting an awning achieves the exact same functional outcome at a fraction of the cost and complexity.

```mermaid flowchart TD accTitle: Solar Heat Gain Window Trade-off accDescr: Comparison of high-gain windows with awnings across winter and summer seasons versus expensive architectural alternatives.

subgraph HighEnd["High-End Architectural Build"] A["High-SHGC south windows + low-SHGC elsewhere"] --> B["Permanent engineered roof overhangs"] B --> C["High design and construction cost"] end

subgraph AwningApproach["The Awning Retrofit Approach"] D["High-SHGC windows throughout"] --> E["Install exterior awnings"] E --> F["Cheap, adaptable, works anywhere"] end ```

In a voiceover insert, the presenter expresses concern that focusing primarily on mixed climates like the Midwest overlooks the severe demands of hotter regions. In an extreme climate like Phoenix, Arizona, even five average-sized (3-by-5-foot) west-facing windows equipped with top-tier low-e glass (SHGC of 0.2) will still admit well over a kilowatt of heat for hours every afternoon. As Alec puts it: “That’s not far off from running a space heater on high, and when it’s 100 degrees outside that’s not the smartest move.” Despite this reality, modern desert home developments frequently omit exterior window overhangs altogether, abandoning simple passive cooling strategies that were common knowledge even in temperate climates like Chicago.

- Five 3×5-foot west-facing windows with an SHGC of 0.2 transmit over 1 kW of thermal energy continuously on summer afternoons. - High-SHGC glass captures passive solar heating in winter; awnings block the steep summer sun without replacing the glass. - Modern suburban construction in Phoenix, Arizona, routinely neglects exterior window overhangs.

---

[13:31](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=811s) Modeling Skepticism and the Indoor Blind Fallacy

Reflecting on the simulation data used earlier, both Alec and the collaborator who helped run the building energy models harbored significant skepticism regarding certain outputs. Specifically, the model suggested that interior dark, closed drapes could reduce cooling power demand more effectively than a 2.5-foot exterior overhang, even when an overhang was already present. This defies basic physical principles: interior drapes cannot prevent sunlight from crossing the building envelope. Once sunlight penetrates the glass, its energy enters the room, and even highly reflective white roller shades absorb substantial energy and become intensely hot to the touch on summer afternoons. Exterior shading prevents the greenhouse effect from starting in the first place.

This disconnect highlights a broader industry problem: independent, robust research on the real-world efficiency of exterior awnings is remarkably sparse. The vast majority of published claims come directly from awning manufacturers rather than peer-reviewed academic or building-code studies. The underlying physics, however, are straightforward: eliminating direct solar beam radiation effectively converts any window—regardless of the façade it is located on—into the thermal equivalent of a shaded north-facing window (or south-facing in the Southern Hemisphere). As Alec notes: “Really, if there’s one call to action I want to make here it would be that there needs to be more study on the effectiveness of window awnings.”

- Interior blinds cannot stop radiant solar energy once it crosses through the glazing, leading to indoor heat absorption. - Shading external glass converts an exposed window into the thermal equivalent of a shaded, north-facing aperture. - Credible energy efficiency data for awnings remains surprisingly scarce outside of commercial marketing materials.

---

[15:14](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=914s) Trade-Offs: Light, Maintenance, Smart Tech, and Pests

Awnings do come with real-world drawbacks, the most immediate being reduced interior daylight. Because their explicit purpose is to eliminate direct sunlight, rooms become noticeably darker, which might disappoint occupants or sun-seeking pets. A speculative alternative could be a transparent awning made of ultra-low SHGC glass, which would preserve a clear view of the sky while cutting radiant transmission. Maintenance presents another historical pain point: early fabric awnings faded, accumulated dirt, and proved tedious to remove from frames, which drove the mid-century popularity of rigid aluminum models.

Modern material science and home automation offer solutions that bypass these old headaches:

```mermaid flowchart LR accTitle: Awning Technological Evolution accDescr: The progression from traditional fabric awnings to aluminum and modern automated smart systems.

subgraph Past["Historical Trade-offs"] A["Traditional Fabric<br>(faded, hard to wash)"] --> B["Rigid Aluminum<br>(durable, fixed position)"] end

subgraph Modern["Modern Automation"] C["Retractable Roller Awning"] --> D["Sensors + Wi-Fi Actuators"] D --> E["'Smart Awning'<br>(retracts for wind/clouds)"] end ```

Modern retractable fabrics paired with motorized rollers, Wi-Fi connectivity, and environmental sensors can automatically deploy during peak solar angles and retract during overcast weather, high winds, or winter days. The final drawback is biological: external shelters attract wildlife. While a nesting robin might be welcome, wasp nests frequently crop up in the framing underneath awnings. Though screened windows protect home interiors from stinging insects, physically clearing nests remains a chore. Nevertheless, Alec finds these minor issues easily manageable compared to the substantial thermal relief awnings provide.

- Fabric awnings historically suffered from UV degradation and difficult cleaning cycles, leading to the rise of aluminum awnings. - Automated motorized roller awnings can deploy on demand and retract during overcast skies or severe weather. - Pests such as wasps often construct nests under the protected eaves of fixed exterior awnings.

---

[17:23](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1043s) Real-World Observations and Competing Exterior Shading

Alec's ongoing experiment of cooling his home exclusively overnight highlights the intense thermal power of solar radiation. On completely overcast summer days, his home's indoor temperature rises by only 5 to 6 °F throughout the entire day. On clear, sunny days with identical outdoor air temperatures, the indoor heat gain doubles to 10–12 °F. While radiant heating of the roof, attic, and exterior siding contributes to this increase, the thermal spike in west-facing rooms is nearly instantaneous as soon as the afternoon sun strikes the unprotected window glass.

```mermaid flowchart TD accTitle: Comparison of Exterior Window Shading Methods accDescr: Comparing awnings, European roller shutters, and exterior porch blinds on airflow and visibility.

A["Exterior Solar Shading Options"]

A --> B["Awnings"] B --> B1["Sun blocked before glass"] B --> B2["Free airflow dissipates heat"] B --> B3["Preserves ground-level outdoor view"]

A --> C["Rolladen / Roller Shutters"] C --> C1["Sun blocked before glass"] C --> C2["Traps warm air pocket against glass"] C --> C3["Completely eliminates outdoor view"]

A --> D["Exterior Porch Blinds"] D --> D1["Effective solar blockage"] D --> D2["Flexible fabric hanging"] D --> D3["Obstructs the outward sightline"] ```

While European exterior roller shutters (*Rolladen*) and exterior drop-down porch blinds effectively block direct radiation, both have clear operational downsides. Rolladen trap a dead-air pocket directly against the windowpane; as the metal slats bake in the sun, they re-radiate thermal energy into that confined gap, warming the glass while completely blocking the outdoor view. Exterior drop blinds also eliminate the sightline outside. An awning, by contrast, creates an open-air canopy that allows warm air to dissipate freely via natural convection while leaving sightlines to the outside completely clear. As Alec notes: “I’d rather have an awning, then that heat isn’t trapped and I can still look outside!”

- Overnight AC thermal flywheel experiments show daytime heat gain doubles (from 5–6 °F to 10–12 °F) on sunny vs. cloudy days at identical ambient temperatures. - European exterior roller shutters (*Rolladen*) trap a pocket of hot air directly against the glazing and completely obstruct daylight and views. - Awnings permit continuous convective airflow to prevent hot air stagnation while keeping outward ground views unobstructed.

---

[19:25](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1165s) HOA Barriers and Final Call to Action

The biggest modern obstacle to widespread awning adoption in suburban housing is the Homeowners Association (HOA). In common-interest developments such as townhome communities, strict architectural control committees routinely forbid exterior modifications. Alec argues that if rigorous scientific research demonstrates that awnings can lower household cooling energy demands by meaningful margins—such as 20%—state or local legislation should curtail HOA authority to ban them outright. At an absolute minimum, HOAs should be mandated by law to provide a pre-approved palette of architectural awning styles and fabric colors.

With climate change intensifying summer heat domes, building codes and property standards must evolve beyond relying entirely on mechanical air conditioning and interior blinds. Historically, awnings were ubiquitous because they solved heat load problems passively. Alec concludes: “If window awnings were helpful before air conditioning, then surely they’re still helpful now.” Modern building science has spent decades optimizing glass coatings while forgetting basic geometric shading techniques that shield the glass altogether.

- HOAs stand as the primary legal and administrative barrier preventing homeowners from retrofitting exterior awnings. - Alec advocates for statutory protections restricting HOAs from banning energy-saving awnings, or at minimum requiring pre-approved styles. - Cooling energy codes frequently overlook window overhangs and awnings, despite their proven historical efficacy before the invention of residential AC.

---

[21:09](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1269s) Outtakes and Bloopers

The video concludes with a sequence of lighthearted outtakes set against background jazz. Alec struggles through multiple takes of his presentation lines, stops abruptly when hearing strange ambient noises off-camera, and remarks humorously on his wardrobe: “I forgot how to tie a tie, I had to look it up! It’s been too long.” He rehearses and fumbles historical phrasing from vintage awning brochures regarding porch comfort, laughs through several verbal slip-ups and exasperated sighs, and brainstorms marketing pitches to make awnings culturally appealing again—riffing on baseball caps for houses before closing on a drawn-out, groan-worthy vocal pun: “*AWWWWW-nings.*”

- Alec humorously admits to having to look up how to tie a necktie for the video segment. - Features scrapped script reads and stumbles over vintage advertising copy describing awnings keeping porches "shaft and pleasant." - Alec brainstorms marketing slogans: "Awnings: like a baseball cap for your house!" followed by a drawn-out pun on the word *awning*.

## Notable quotes > [19:25](https://www.youtube.com/watch?v=uhbDfi7Ee7k&t=1165s) If window awnings were helpful before air conditioning, then surely they’re still helpful now. — Alec

## Mentioned Technology Connections, Alec, Building Age and National Builder, Hal and Helen Davis, Better Homes and Gardens, Google Street View, Patreon, Mastodon, Bluesky

## Video description Seriously - where'd they go? Links 'n' stuff:

Technology Connections on Mastodon: https://mas.to/@TechConnectify

Technology Connections on Bluesky: https://bsky.app/profile/techconnectify.bsky.social

Have you ever noticed that I've never done a brand deal? That's all thanks to people like you! Viewer support through Patreon keeps this channel independent and possible. If you'd like to join the amazing folks who fund my work, check out the link below. And thank you! https://www.patreon.com/technologyconnections

[Source](https://www.youtube.com/watch?v=uhbDfi7Ee7k)

中文简报

遮阳篷：一项被我们遗忘的简易降温技术该视频探讨了窗户遮阳篷如何从20世纪初建筑中不可或缺的被动降温构件，转变为在20世纪中叶房地产市场中被贴上过时标签并被家用空调所取代的设计。结合建筑能耗模拟与太阳几何学，主讲人展示了室外遮阳篷可在不产生静态低太阳得热系数（low-SHGC）窗玻璃所带来的冬季采暖负效应的前提下，削减约20%的年度制冷负荷。在指出减弱自然采光、昆虫筑巢和维护需求等弊端的同时，视频还将遮阳篷与室内百叶窗及欧洲卷帘进行了对比并肯定了其优势。最后，视频呼吁对遮阳篷性能展开专门的学术研究，并推进立法改革以阻止郊区业主委员会（HOA）禁止外遮阳改造。针对芝加哥标准住宅的能耗模拟显示，在阳光照射到玻璃前加装室外窗户挑檐阻挡辐射，可将年制冷能耗需求减少20%。 (7:56) 静态低太阳得热系数（low-SHGC）窗玻璃虽能降低夏季制冷需求，但在较寒冷气候区会因永久阻挡免费的被动太阳得热，而导致严重的冬季采暖能耗代价。 (7:56) 室内百叶窗和窗帘无法阻挡辐射热增益，因为热量已经穿透建筑围护结构并被表面吸收，从而通过温室效应推高室内温度。 (13:31) 业主委员会（HOA）是推行现代遮阳篷的最大行政阻碍，这促使人们呼吁出台类似于太阳能板使用权法案的立法保护。 (19:25)

Source quotes

[19:25] Alec: If window awnings were helpful before air conditioning, then surely they’re still helpful now.

Original transcript

[0:00] You ever reach way back into your brain [0:02] and uncover something from the not-too-distant past that seems weirdly obvious yet isn’t popular anymore? [0:09] That’s right, I’m talking about window awnings! [0:12] You used to see these everywhere, especially on those cute brick ranches kitty corner to the house where you grew up - [0:18] I’m sure that’s a universal experience. [0:20] But lately, they’ve fallen out of fashion. [0:22] And I would like to make the case that we should get them back. [0:25] Quick programming note, I’m not gonna be recommending any specific kind of awning or product line or anything like that. [0:32] I am not here to sell you anything [0:35] ...YouTube ads notwithstanding... [0:36] though I do like spreading ideas. [0:39] And awnings are one of those ideas that our ancestors figured out but as far as I can tell we just decided we’re too cool for these days. [0:47] Which is ironic because window awnings keep you cool. [0:50] That’s their point! Or at least, a central point. [0:54] See, we like windows. [0:56] [WIndows XP error sound] Maybe not that kind, but that kind is pretty universally liked. [1:01] They let in natural light and allow us to look outside and see things. [1:05] But windows are also great big holes in walls which we only plugged with thin sheets of glass. [1:12] While they have gotten surprisingly good over the years at keeping heat energy from moving through them, [1:18] they’re still nowhere near as good as the thick walls which surround them. [1:22] And, here’s the important bit to this video, [1:25] they become a major source of heat gain when the sun shines through them. [1:30] Ever heard of the greenhouse effect? [1:32] That doesn’t just happen in greenhouses, it happens any time the sun’s energy makes it through a transparent window and into an enclosed space. [1:40] Like your house. [1:42] Once sunlight makes its way into your home, it lands on the stuff inside like flooring, furniture, et cetera. [1:48] That stuff absorbs the sun’s light energy which is then re-radiated into your home as heat energy. [1:55] This heat gain from solar irradiance, in the context of buildings, is called insolation. [2:01] Not insulation - but insolation. [2:05] Don’t look at me, I just work here. [2:07] Thanks to recent innovations in coatings on the glass, a lot of this energy is reflected away and kept out of your home. [2:14] But, fun fact, the sun is extremely powerful so even with really fancy windows there’s a lot of energy getting inside that ultimately becomes heat. [2:24] Don’t take my word for it, just ask a cat. [2:27] In the winter months this warmth can be a pretty nice benefit, [2:30] but in the summer months - it sucks. [2:34] And our ancestors knew this. [2:36] They figured out that if you designed a structure so that the windows couldn’t be in direct sunlight, [2:42] then there would be no greenhouse effect and the interior of that structure would stay much cooler. [2:48] Those grand covered porches you see on fancy old houses throughout much of the Southern US weren’t just for enjoying the breeze, [2:55] they kept the windows entirely shaded. [2:58] In fact they kept pretty much the entire structure shaded. [3:02] And it wasn’t just plantation houses - the galleries attached to historic French Quarter buildings also help keep the buildings cool. [3:09] Notice how the building is in direct sunlight here but almost the entire structure (other than the roof) is in shade. [3:17] Of course, those examples have multiple purposes. [3:19] I can’t earnestly say that shading windows was “the point” of a covered porch. [3:25] It also created a pleasant outdoor space and protected windows and doors from the elements, allowing you to leave them open in a rainstorm. [3:32] But we did recognize the value of that coverage. [3:35] So much so that in the not-too-distant past, [3:38] there were popular products for your home which provided the shade and cover of an opulent wraparound porch but with minimal materials and easy installation. [3:48] What products, you ask? [3:50] Awnings! [3:51] It appears these really came into vogue in the 1920’s. [3:54] This 1927 article in Building Age and National Builder comes out swinging: [4:00] “A Beautiful home which is devoid of awnings resembles a well dressed man without a necktie. [4:05] The awnings give that finishing touch, just the last point to complete the proper taste.” [4:10] Seems like the author really likes awnings! [4:13] But why? [4:15] It’s all about keeping comfortable! [4:17] “An awning on the porch permits the use of the porch when the hot afternoon sun is shining. [4:22] They will keep the porch shady and pleasant, and this also reduces the temperature of the rooms adjoining the porch.” [4:28] And here’s my favorite part: [4:30] “The fact that the awning excludes the sun from the window glass is quite an important asset in reducing the temperature of the room, [4:37] and in preventing the fading of wall paper and carpet.” [4:41] Sure seems like awnings are the cat’s meow! [4:44] In 1925, Hal and Helen Davis wrote in Better Homes and Gardens [4:48] “Awnings - they have such possibilities, such delightful possibilities, that foolish indeed is a house to go without them, if they can be afforded.” [4:57] That’s right, we just got called fools by the Davis family! [5:01] Honestly this article is a useful tool for understanding how they were spreading. [5:05] It even breaks down the differences in awning configurations by locale and the pros and cons of various types. [5:12] This used to be a big deal! [5:14] And they were a selling point for your home - [5:16] real estate firms are beginning to learn the value! [5:19] Plus they’re just a fun accent piece. [5:21] I mean, who wouldn’t want to flaunt their unusually picturesque nature with a cool set of Arabian Awnings? [5:28] The spears really sell it. [5:30] But hundred year old magazine articles are one thing and the real world is another. [5:35] How big were awnings really? [5:37] Well, if you dingle around on the ol’ Streetview and visit practically any old Chicago neighborhood, [5:42] you’ll find plenty of houses which still have exterior window awnings providing that overhang for shade, especially on South and West-facing windows. [5:52] You can see in this image how effective they are: [5:55] this side of the house is being hit with direct sunlight, but the awning is almost entirely shading the window below it. [6:02] Thanks to that awning, the old front room is staying much cooler than it would without it. [6:07] Many of these products also allowed you to leave windows open in the rain - at least if they were installed correctly and you had the right kind of window. [6:15] They offered a lot of benefits! [6:17] Yet despite remaining extant in various styles, [6:21] the functional purpose of window awnings seems to have almost entirely left the public consciousness. [6:27] Why’d this happen? [6:29] I’m gonna say it’s a mix of two factors: air conditioning and fashion. [6:34] The advent of mechanical air conditioning diminished the importance of the passive tricks we used to rely on to keep cool. [6:41] As more and more people started hooking up energy-consuming air conditioners to the power grid [6:46] (boy I hope it can keep up with all that… sorry wrong topic). [6:51] As more and more people got air conditioning, suddenly the temperature in their home was controllable. [6:57] And so long as those air conditioners were powerful enough to overcome the heat gain of solar irradiance, [7:03] the awnings that previously helped keep us cool in a heatwave didn’t seem necessary any longer. [7:09] And, technically, they weren’t. [7:12] So, fast forward a decade or two, and new homes are getting built without them. [7:17] No need for awnings when we can pump the heat right out! [7:20] That meant that all the older homes with awnings started to look dated. [7:25] And if there’s one sin in the fashion world, it’s looking dated. [7:30] As you can tell I take this very seriously. [7:33] Beyond fashion, though, awnings on a home may very well have been a sign that the home didn’t have air conditioning, [7:39] and I’ll bet many a realtor in the 1960’s suggested taking them down. [7:45] "No one wants a house with awnings," they’d say, "those are for old fuddy duddies. And poor people." [7:51] And now, other than that one infomercial, awnings are largely forgotten. [7:56] But dang it, I think it’s time for us to consider bringing them back. [8:00] For one, I actually think window awnings are pretty cute. [8:04] Maybe not the aluminum ones that you still run across sometimes, though hey - they sure proved their longevity. [8:10] But there are so many different styles of awning out there, plus many more to be discovered. [8:16] And like those 1920’s people, I think window awnings offer a real way to put a personal touch on a home. [8:23] And what’s cooler than a way to express yourself that also literally keeps you cool? [8:28] There’s a lot to like about them! [8:30] Heat waves would be a lot more manageable with window awnings keeping the sun’s heat outside your home, [8:36] and day to day they save money on electricity bills. [8:39] How much money? [8:41] Well, unfortunately, that’s not the easiest thing to answer. [8:45] It's annoyingly hard to get an idea of how much heat energy is actually coming through a window when the sun shines through it. [8:52] It depends on so many factors: your location on the planet, the direction the window faces, the time of the year, time of day, [8:59] and of course the performance of the window itself all matter a lot. [9:04] Still, I wanted to give you some useful information so I reached out to someone who has access to modeling software which can predict the energy needs of a home. [9:14] They took a typical house in Chicago and ran some numbers for heating and cooling demand while tweaking a few variables. [9:21] There’s a lot of interesting stuff to cover here but what I want to highlight first is this: [9:26] Doing nothing to the house but adding window overhangs reduced the annual cooling energy needed by 20%. [9:35] That’s a big deal! [9:37] But you’ll notice that other things had an impact, too. [9:40] And if you notice even harder, you’ll see that those impacts were all double-edged. [9:46] In the past, I’ve mentioned Low-E windows. [9:50] That’s kind of a catch-all term and doesn’t mean a whole awful lot on its own, but broadly it just means high-performance windows. [9:57] And one of a window’s performance metrics is the solar heat gain coefficient. [10:03] You can think of this as the percentage of the sun’s heat energy that makes it through the glass. [10:08] There are windows on the market now with exceptionally low SHGCs: some windows don’t even let a quarter of the sun’s energy through, [10:17] and those are great to have in warm climates where you rarely ever need to heat buildings. [10:23] But they’re often not a great fit for us up North because over the course of a year we need more heat energy than we need cooling, [10:31] and blocking the sun’s free heat doesn’t make much sense. [10:35] Notice that in our modeling, [10:37] swapping out just the South facing windows to a lower SHGC [10:42] dropped cooling demand a pretty similar amount to adding overhangs. [10:47] But look what it did to the heating demand. [10:50] It went up significantly because those windows are actually working against us in the winter. [10:56] Our winters suck and some free heat from the sun is a very welcome thing. [11:01] So there’s a tradeoff to changing the window’s thermal performance characteristics. [11:07] And have you noticed what the lowest total annual power figure came from? [11:11] Windows with high solar heat gain coefficients for free heating in the winter but which had overhangs to block sunlight in the summer. [11:21] That’s the beauty of awnings. [11:23] We don’t have to make the choice between winter and summer performance when buying a window. [11:28] We could use a window best-suited for winter heat gains and then in the summer just block the sun from hitting it with an awning. [11:37] The reason why I’m making this video now is that, well, it occurred to me that there isn’t really a difference [11:43] between a properly-installed window awning and some of the rather advanced home design techniques we see today. [11:50] Those with lots of money to spend when designing their new custom homes might get fancy and install different window types. [11:58] One method I’ve talked about before is installing high heat-gain windows below an overhang so they provide that free heat in the winter but not in the summer. [12:07] And then use low-heat-gain windows elsewhere in the house. [12:10] That’s a cool idea but it’s a lot of work compared to slapping on an awning! [12:15] And the best thing about slapping on an awning (besides how fun that is to say) is that it can be done cheaply and anywhere! [12:22] Speaking of anywhere, here’s a clunky voiceover edit. [12:26] I’m worried that I fixated too much on the scenario we face here and not enough on warm and hot climates. [12:32] Because even if you’ve got the best dang windows on the market with an SHGC of .2, five average-sized West-facing windows (I’m calling 3 by 5 feet average) [12:44] are going to let in more than a kilowatt of heat for several hours every afternoon. [12:49] That’s not far off from running a space heater on high, and when it’s 100 degrees outside that’s not the smartest move. [12:57] For giggles I decided to look at some new homes getting built around Phoenix, Arizona [13:02] and it’s frankly astonishing to me that in that climate there’s apparently no focus paid on window overhangs. [13:10] Sure, back in the day we didn’t have the fancy glass we do now, [13:14] but if window awnings were popular here in Chicago, where it’s really only hot 4… maybe 5 months of the year, [13:22] it seems to me like there’s a lot of energy and money being wasted by not thinking of ways to keep windows in the shade. [13:31] Now, there's a couple of notes I want to add. [13:33] Both myself and the person who helped me with the modeling here are a bit skeptical of some of the data it spat out. [13:41] The impact of dark closed drapes when there’s already a 2.5 foot overhang seems really high, [13:49] and the fact that those drapes by themselves are lowering cooling power more than the overhangs seems… impossible. [13:58] Drapes on the inside of a window don’t stop sunlight from passing through the window glass. [14:04] At best, if they’re very reflective, they can push some of the sun's energy back out [14:10] but having stood next to a West-facing window with a white roller shade, I can say from experience that that shade gets pretty stinking hot on summer afternoons. [14:20] It is always better to keep the sun from coming through the glass in the first place, that way there is no greenhouse effect, [14:27] so how this model is considering those factors seems a bit off. [14:32] Really, if there’s one call to action I want to make here it would be that there needs to be more study on the effectiveness of window awnings. [14:41] It’s quite strange how little information there is on this topic, [14:45] and most of what I’ve found are claims from awning manufacturers so I’m not exactly taking them seriously. [14:52] But it does seem pretty obvious to me that if you can eliminate direct sunlight transmission through a window, [14:58] then you’re effectively turning any window into a North-facing window no matter which side of your house it’s on. [15:05] And that could make a dramatic difference in the warm parts of the year. [15:10] Unless you’re in the Southern hemisphere in which case, strike that - reverse it. [15:14] Now, it’s not like awnings don’t come with any drawbacks. [15:18] Most obvious is that they make the interior of your home much darker during the day. [15:23] If the awning is made of a translucent material you could still get plenty of filtered light coming through the window, [15:29] but its entire purpose is to eliminate direct sunlight and if that’s something you or your cat appreciates, well a proper awning is going to eliminate it. [15:40] Although, I am quite curious about the potential effectiveness of a transparent awning made from glass with a really low solar heat gain coefficient. [15:50] That might be a way to have the best of both worlds. [15:53] And it would leave your view of the sky mostly unimpeded. [15:56] Then there’s maintenance. [15:58] The aluminum ones that still hang around were designed in response to the fiddle factor of fancy fabrics. [16:05] Those fabrics would fade with time and required periodic cleaning, and depending on the design of the support structure, [16:12] removing the fabric from the awning could be a pain in the butt. [16:16] A rigid awning made of aluminum mostly took care of these problems, and that’s most likely why they started spreading. [16:23] Then again, materials science has improved dramatically since awnings went out of fashion, [16:29] and some fabric awnings can be selectively deployed. [16:32] A roller-awning can be retracted when you don’t need or want it, [16:36] and don’t look now but throw some Wi-Fi and actuators into the mix [16:41] and you’ve got yourself a Smart Awning that could deploy exactly as much as needed and stay retracted on cloudy days or in inclement weather. [16:50] The last main drawback to awnings that I can think of is pests. [16:55] Through providing shelter for your window you’re also providing shelter for living creatures, and while I’d be pretty cool with a robin’s nest outside my window, [17:03] a wasp nest is less cool. [17:06] Then again, if the window is screened it’s not like that really matters all that much [17:10] but I’ve dealt with my share of wasp nests and usually it’s best to not have to deal with them. [17:15] But to be honest, all of those drawbacks seem pretty minor to me, and many of them aren’t even a thing all the time. [17:23] I can tell you that I would freaking love some awnings on my home - particularly on the West side. [17:29] I’m still doing that thing where I only run the air conditioning in the overnight hours [17:33] and one of the most interesting things that technique has revealed is the dramatic effect of the sun. [17:39] On cloudy days, even though it might be quite hot outside, my home only heats up by 5 or 6 degrees Fahrenheit over the course of the day. [17:48] But if it’s a sunny day at the same temperature, that just about doubles. [17:54] Of course, not all of that is heat from the windows - the attic’s also getting stupid hot from the sun, and so are the walls. [18:01] So it’s not easy to isolate that variable. [18:04] But I can say it is truly remarkable how quickly the rooms on the West side start to heat up once the sun reaches those windows. [18:12] Awnings aren’t the only solution, of course. [18:15] There’s been a whole bunch of Europeans just champing at the commenting bit to let you know all about those exterior roller shutters they’ve had over there for a while. [18:23] Those are interesting, and they’re starting to be sold here, [18:27] but I’m curious to know how hot those shutters get in the sun. [18:32] When closed they seem to trap a bit of air between them and the window glass, so while I have no doubt they’re blocking the sun, [18:40] it seems to me like the window will be getting quite warm as the shutters radiate their absorbed heat into that airspace. [18:48] I’d rather have an awning, then that heat isn’t trapped and I can still look outside! [18:53] Then there are exterior blinds. I’m starting to see these spread, often on porches. [18:59] They’re basically the same idea as Rolladen but usually fabric and not integrated into the window frame or anything. [19:06] Again, those will absolutely do the job of blocking sunlight from hitting the window, but they also block the view when in use which awnings don’t, [19:14] at least not the view out. [19:17] If I seem gung-ho about awnings, well I am! [19:20] I think they’re cool and have been tragically overlooked for the past half-century. [19:25] Which brings me to one last thing. [19:27] I live in a townhome which means if I wanted to install window awnings, I’d need to get the HOA involved. [19:34] And that’s not fun. [19:36] So - circling back to that earlier call to action where I said we should do more research on them, [19:41] if it turns out that window awnings actually could reduce a typical home’s cooling costs by 20%, [19:48] then whaddya say we go ahead and neuter an HOA’s ability to forbid their installation? [19:54] Or, if that sounds too extreme, at the very least force HOAs to offer an assortment of approved styles and colors. [20:01] Something tells me we’re going to want to find more and different ways to keep cool as these heat domes keep happening, [20:08] and if something as simple as a window awning is as useful as it seems to be, uhh we should probably encourage their use. [20:17] Alright, well that’s it! [20:19] If anyone out there is involved in evaluating building energy codes and all that fun stuff, please chime in with any info you might have on this topic. [20:28] I really didn’t find anything specifically about awnings and how much they could reduce cooling costs, [20:35] and from what I’ve heard there really isn’t much attention paid to the effects of window overhangs at all outside of hyper-nerd circles. [20:44] If window awnings were helpful before air conditioning, then surely they’re still helpful now. [20:50] And given how a lot of new housing stock, even in places like Arizona, is getting built without window overhangs at all, [20:58] either these new windows are miraculous marvels or we just kinda forgot the tricks of the past. [21:05] Here’s to giving some of them another go. [21:09] ♫ blisteringly smooth jazz ♫ [21:14] …pretty universally liked. [21:16] They let in natural light and allow us to look outside and see things! [21:20] But… what was that? [21:22] Probably nothing you heard but I stopped anyway. [21:24] There’s gotta be two good takes in there. [21:27] I forgot how to tie a tie, I had to look it up! [21:30] It’s been too long. [21:31] Those grand covered porches you see on fancy… [21:35] I am restarting this line. [21:37] An awning on the porch permits the use of the porch when the hot afternoon sun is shining. [21:42] They will keep the porch shaft and pleasant, [21:44] and this also reduces the temperature - I can skip the rest of this line because I already recorded the thing with the tie. [21:49] That might be a way to have the best of both worlds. [21:51] And it wood pfftehh…. [21:53] [falls apart] [21:55] [angry sigh] [21:59] OK, so we gotta come up with some sort of pitch. [22:01] Oooh, pitch. [22:03] Baseball! [22:04] Awnings: like a baseball cap for your house! [22:08] Or maybe.... [22:10] AWWWWWW [22:12] nings.