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conscious living: cool spaces 05 – sunshades

Bahay kubo in CELL, Cavite

A green space is a space that is built with the local climate in mind. Our country is a tropical climate. And one of the major difficulties of tropical climates is cooling interior spaces.

Cooling a space mechanically generally takes up as much as 50 percent of the electricity bill. By cutting down on your use of the air-con, not only do you save energy and money, but also any greenhouse gases that may have been emitted by the production of electricity. This series looks at the various ways of being comfortable without turning on the energy.

Sunshades

One of the most efficient ways of preventing direct sunlight from entering spaces is providing sunshades.

Sunshades are horizontal or vertical elements that are strategically placed at windows and other openings to directly block the sun’s rays at any given time of the day. Sunshades can also protect the exterior face from added heat gain, keeping the interior cool. There are certain structures that even placed them on the roof!

Window overhang. Photo by Jacob Termansen from Tropical Style by Gillian Beal (2003)

Sunshades come in all shapes and sizes. They can be large fins at the sides of a window or a group of flat louvers covering it entirely. They can also be a lattice or mesh covering the entire structure. They can be made of steel, aluminum, concrete or wood. Plants, specifically vines and hanging varieties, can also be allowed to creep over exterior supports (and if it’s a fragrant, flowering kind, can generate a nice scent inside when the wind passes through).

Vertical louvers. Photo by Jacob Termansen from Tropical Style by Gillian Beal (2003)

Here is the rule of thumb for the use of sunshades. For north or south-facing windows, use horizontal sunshades due to the vertical position of the sun. For east or west-facing windows, use vertical sunshades due to the low angle of the sun at mornings and late afternoon.

The size and design of sunshades can be computed based on the orientation, location and size of the window. Just ask your capable designer (make sure he/she knows the formulas). Or you can download The Solar Tool from the internet (http://ecotect.com/products/solartool).  Try the trial version for free!

Wide roof eaves of the Manosa house

If you have a limited budget, think about redesigning the biggest sunshade you may already have – the roof eaves! Lengthen the roof eaves to at least two meters. Consider lowering and extending the roof line (if your roof is sloped) to at least eye level and partially protecting your windows. That way, even while standing up and the sun is low on the horizon, you will not experience glare.

Previous: proper orientation, maximize openings, cross ventilation , stack effect

Next: elevate, ventilate and insulate

conscious living: cool spaces 04 – stack effect

A green space is a space that is built with the local climate in mind. Our country is a tropical climate. And one of the major difficulties of tropical climates is cooling interior spaces.

Cooling a space mechanically generally takes up as much as 50 percent of the electricity bill. By cutting down on your use of the air-con, not only do you save energy and money, but also any greenhouse gases that may have been emitted by the production of electricity. This series looks at the various ways of being comfortable without turning on the energy.

Stack Effect

Hot air rises. Cold air sinks.

In essence (and without getting too technical), this is what stack effect means in tropical climates. It is a scientific fact that air movement in interior spaces follows these directions: up for hot and down for cold.

How does stack effect influence the design of spaces?

Illustration by Arch. Stanley Fernandez

Let’s start with a typical room. Having taller or higher windows allows hot air to escape above. It also implies that a higher ceiling is beneficial in keeping the heat as far away from the living zone.

(This is also the main reason why air-conditioning units should be placed above or near the ceiling, so the cold air could naturally sink and not overwork the motor. Overworking the motor leads to consuming more energy. But we’re advocating natural ventilation here as much as possible.)

If the building or house is multi-story, the ground or lower levels are usually cooler than the floor right under the ceiling. Place the important spaces (or where you spend the most time in) on the cooler levels.

In his own home, National Artist for Architecture Bobby Mañosa located the bedrooms on the ground floor. To him, having a cool, comfortable space to rest and sleep in is more essential. The living room, dining room and kitchen are located above (which are quite open and ventilated too).

Stack effect can also be used to divert the hot air out of the space. Chimneys or flues can act as passages for heat to rise and escape. Since chimneys are quite impractical in this climate, stairwells become the main avenue for the hot air. Ensure the release of hot air by providing egresses above the stairwell. The openings can be operable louvers or clerestory windows.

Previous: proper orientation, maximize openings, cross ventilation

conscious living: cool spaces 03 – cross ventilation

A green space is a space that is built with the local climate in mind. Our country is a tropical climate. And one of the major difficulties of tropical climates is cooling interior spaces.

Cooling a space mechanically generally takes up as much as 50 percent of the electricity bill. By cutting down on your use of the air-con, not only do you save energy and money, but also any greenhouse gases that may have been emitted by the production of electricity. This series looks at the various ways of being comfortable without turning on the energy.

Cross Ventilation

We discussed the importance of natural ventilation last week in cooling spaces. By having ample sizes and proper orientation of openings, natural ventilation can be introduced. But how does it really work?

Cross ventilation is forcing the wind, with its cool exterior air, into the space, and forcing the hot interior air out. The two important elements (aside from the wind) in inducing cross ventilation are the inlet and outlet.

Cross Ventilation: Illustration by Arch. Stanley Fernandez

The inlet and outlet are the openings we talked about last week, whether they are windows, doors, vents or other openings. The inlet is where the wind enters the space and the outlet is where it exits. To have air movement inside the space (comfortable enough like a cool gentle breeze), there must be an entrance and an exit for the wind to cross to.

Ideally, these two openings should never be side by side. (There happens to be no space to “cross” through.) Their locations should be either at opposite walls or perpendicular to each other. Consequently, it is always best for rooms to have at least two sides facing the exterior to satisfy this condition.

The inlet opening should at least face the direction of the prevailing wind. (That’s why we tackled proper orientation of spaces!) If for some reason it can’t, you can somehow redirect the wind to the inlet by placing “blocks” to bounce the wind right into the opening (of course, just not as efficient).

Try not to put blockages in the path of the wind from the inlet to the outlet. Push those tall furniture and decorative dividers away. And no, light partitions even if they are perforated, will greatly diminish the air speed inside the space. To have the maximum effect of cross ventilation, air flow should be unimpeded.

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Next: stack effect

conscious living: cool spaces 02 – maximize openings

A green space is a space that is built with the local climate in mind. Our country is a tropical climate. And one of the major difficulties of tropical climates is cooling interior spaces

Cooling a space mechanically generally takes up as much as 50 percent of the electricity bill. By cutting down on your use of the air-con, not only do you save energy and money, but also any greenhouse gases that may have been emitted by the production of electricity. This series looks at the various ways of being comfortable without turning on the energy.

Maximize Openings

Natural ventilation is one of the most efficient ways to cool the interior space. It involves creating internal air movement, just strong enough to feel comfortable but weak enough not to blow all the paper around. By circulating the air inside the space, the hot air is pushed outside and the cool air is carried inside.

Last time, we tackled the proper orientation for your desired space. There are two important directions to consider for our country: northeast and southwest. Generally, at any time of the year, prevailing winds travel from these two points. Northeast monsoon (hanging amihan) occurs during the cold months and southwest monsoon (hanging habagat) starts during the summer months. PAG-ASA (Philippine Atmospheric, Geophysical and Astronomical Services Administration) even has localized data on prevailing wind directions specific to cities and municipalities. By having ample windows and openings facing these directions, we can have guaranteed air movement to enter the space.

To maximize ventilation, one also needs to maximize the openings. Having large operable (that you can open) windows is ideal. Increase the size of your windows. Lower the height of the window sill while extend the height of the window up to the ceiling line. Old ancestral houses even have window openings at the top and bottom of regular windows called ventanillas to allow as much air as possible. These can have louvers or screens instead of unobstructed openings to preserve the privacy of the users.

The optimum type of window to specify is the one that maximizes the opening; that means it can be fully opened 100%. Sliding windows for instance can only have a maximum opening of 50%. Awning-type windows have 60-70% openings. Casement types (swing-out like cabinet doors) have 100 percent openings. Jalousie windows or louver types can also have 100% openings, plus having the distinct advantage to adjust the air flow by manipulating the panels.

To screen or not to screen? Common insect screens restrict air flow by as much as 50 percent. There are imported types that impede less, but they are generally more expensive. If the space is not that critical or located atop a high-rise building, I suggest opening up your windows. Use screens only on sensitive areas like bedrooms and nurseries. Besides, there are house plants that deter mosquitoes and other insects.

So maximize natural ventilation for your spaces and minimize your energy costs for cooling.

Previous: proper orientation

Next: cross ventilation, stack effect

i saw design: ang pinakamagandang bahay sa balat ng lupa

Green Guide told us about this exhibit in UP Theater culminating the design competition entitled “Ang Pinakamagandang Bahay sa Balat ng Lupa” (The Most Beautiful House on the Face of the Earth). It showcases the winning designs for both the Student and Professional categories, as well as other remarkable entries. A joint project of the UP College of Architecture and Lafarge Semento Pilipinas, the competition aimed to redefine the concept of “the beautiful house”. With a focus on sustainable architecture, entries provided complete architectural designs for a medium-income house to be built on a 200-square meter lot inside the UP Diliman Campus.

Apart from the green strategies that the winning entries consciously incorporated into their respective designs, I also noticed that they all came up with interesting forms for the architecture of the house. I think it was from the book Green Architecture (sorry I forgot the author. Maybe you can help me, Green Guide?) where I read that green designs should not only propose sustainable design techniques and strategies, but should also provide a new face, a new aesthetics to accompany the philosophy. The new visual form makes it easier to promote to everyone the concept of sustainability by becoming a symbol for the message, as well as a source of inspiration.

(The winners for the Professional Category, from left to right: Borloloy House by John Patrick Buensalido, et. al.; EcoKubo by Nestor Arabejo, et. al.; and [X] House by Jose Eduardo Calma, et. al.)

I agree with the judges’ pick for the first place. What I love about its design is its unique form–unpredictable, sculptural, and organic.

(The winners for the Students Category, from left to right: Tulad ng Dati House by Laurence Angelo Angeles, et. al.; Pinakamagandang Bahay by Mark Angelo Virtucio, et. al.; and Cube-O House by Deneice Yuson and Zada Ong.)

Among the winning designs for the Student Category, I especially like the Cube-O House. I can imagine the trellis filled with flowering white thunbergia!

The PMBBL exhibit runs until Oct. 23, Friday, at the Forefront Gallery of the UP University Theater.

*images of the winning entries are from the PMBBL monograph

conscious living : cool spaces 01– proper orientation

A green space is a space that is built with the local climate in mind. Our country is a tropical climate. And one of the major difficulties of tropical climates is cooling interior spaces.

Cooling a space mechanically generally takes up as much as 50 percent of the electricity bill. By cutting down on your use of the air-con, not only do you save energy and money, but also any greenhouse gases that may have been emitted by the production of electricity. This series looks at the various ways of being comfortable without turning on the energy.

Proper Orientation

One of the best tools you can apply to your space is a compass. Finding the orientation (where the north, east, south and west) of the space will help a lot in identifying, literally, the hot spots.

For our country, the sun (the major source of heat) travel, most times of the year, from east to west in a southern path everyday. From that alone, at any time of the day, three out of four sides of your space is exposed to the direct rays of the sun. Plus, the tropical sun, coupled with the thinning ozone layer and little cloud cover, can be quite intense. The sun can be found at the east in the morning, south at noon, and west in the afternoon. That leaves north as the coolest part.

Diagram by Arch. Stanley Fernandez

Let’s say you’re building your dream house. You place at the north side of your home the important spaces or rooms you spend the most time at during the day. It can be the bedroom or the den. You can place large window facing northwards, assured that no direct sunlight shall enter that room. (The absence of direct sunlight does not necessarily mean dark spaces. The intensity of the tropical sun can light up spaces indirectly.)

It’s also a lot easier if you want the space cooler because you are not starting from a higher temperature. An additional fan (that coincidentally uses a lot less energy than an air-con) may be all that’s needed.

You normally want to put the service areas at the hot parts (east and west) of the house. That can be the kitchen, laundry, bathroom or other spaces you spend time in fleetingly.

So, save up on future energy costs by just finding the right places for your spaces.

Next: proper orientation; maximize openings; cross ventilation; stack effect