Tag Archives: passive design

Amory B. Lovins on Integrative Design

I’m going to give you a little bit of homework before we get into the meat of this post. Watch this video:

(I’ve probably posted that before. I’m a wee bit obsessed with Mr. Lovins and his work)

Now let’s talk a little bit about integrative design. Integrative Design is a method of design based on working from the top down. Basically you look at the entire system – the entire car, the entire house, the entire factory, with the intention to make it as energy efficient as possible. By looking at design from the top down you ask how to make the best holistic design by intertwining the functions of the different components.

Integrative Design is different from traditional design methods which focus on optimizing each individual piece of the system and then fitting them together and adjusting how they interact. This traditional method creates the most optimized walls and plumbing and HVAC. But the integrative design approach allows you to say, what if we didn’t need the HVAC at all  (or at least not our idea of the most optimized HVAC) because we change the way we build the walls completely.

At the end of the Autodesk video Amory mentions the 10xE principles of integrative design, and I want to share those here:

  1. Define shared and aggressive goals.
  2. Collaborate across disciplines.
  3. Design non-linearly.
  4. Reward desired outcomes
  5. Define the end-use.
  6. Seek systemic causes and ultimate purposes.
  7. Optimize over time and space.
  8. Establish baseline parametric values.
  9. Establish the minimum energy or resource theoretically required, then identify and minimize constraints to achieving that minimum in practice.
  10. Start with a clean sheet.
  11. Use measured data and explicit analysis, not assumptions and rules.
  12. Start downstream.
  13. Seek radical simplicity.
  14. Tunnel through the cost barrier.
  15. Wring multiple benefits from single expenditures.
  16. Meet minimized peak demand; optimize over integrated demand
  17. Include feedback in the design.

In Amory’s lecture he talks about using integrative desing in building design for heating and cooling, in auto design for using less fuel, and in factory design for pumping fluid. Stay tuned for a bit of a deeper dive into these topics in the future, including how the integrative design principles lead to radically different approaches in each of these categories.

solar water heater

Passive Water Heaters

The last topic I’m going to cover in this series on passive design is passive water use. Heating water consumes a considerable chunk of the energy that the typical house uses, so if you can cut your active water heating it can pay off both in terms of cutting energy use and cutting your bills.

While passive solar water heating systems are less efficient than their active counterparts, they tend to be cheaper, reliable, and long lasting. There are two basic types of passive water heaters, the integral collector-storage passive system or a thermosyphon system.

Integral Collector-Storage  (ICS) Passive Water Heater

An ICS system works best in more moderate climates, where the temperature rarely falls below freezing.  The ICS system has exposed pipes, so above freezing temperatures are necessary to keep the pipes from freezing and ruining the system.  The ICS system is made up of an insulated storage tank, a solar collection tank and the pipes that connect them. The solar collection tank is used to heat water in batches using solar energy. Once heated, the water passes into the insulated storage tank, and cool water fills the solar collection tank again.

Thermosyphon Passive Water Heater

A thermosyphon consists of a tank, pipes and a solar circulator. In this case instead of the sun heating a large tank of water, the sun heats winding pipes of water. Cool water flows from the high positioned tank into the lower circulator where it is heated. Warm water flows from the circulator back into the tank due to natural convection caused by the temperature gradient.  An indirect thermosyphon that uses glycol fluid in the circulator loop can be used in colder climates if the piping is adequately insulated.

If you’re interested in building your own passive water heater, you can find some good information here.

photo: “Solar Water Heater boiler” by gmourits CCBY

 

Passive Cooling through Ventilation

Our ancestors came from hot climates, so we’ve been working on keeping the shelters we live in cool for ages.  There are a number of different ways to accomplish this, and today I’m going to write specifically about ventilation. Moving air is incredibly effective at cooling – especially at cooling people -because it helps sweat or other water evaporate. Think about it, have you ever been sweaty and stood in front of a fan? You cool off quickly, even to the point of getting a chill as the moving air evaporates your sweat.

Here are four methods of ventilation that are used around the world to help keep our homes and other buildings cool.

Cross Ventilation

Cross ventilation relies on wind moving through a space. You’re probably already familiar with the fact that if you open two windows across the room from each other, you are going to get a better breeze through a space than if you only open windows on one side of a room. Because of this, open floor plans can be great for passive cooling through ventilation. An important factor to note is that the two openings – the inlet and the outlet – should be of equal size, or the outlet should be larger for optimal air flow.

Stack Ventilation

Have you ever noticed the slated window on the top level of a house? This is a gable vent, for stack ventilation. Hot air rises and escapes through these openings. As it does so, it causes a pressure difference between indoors and outdoors, and this causes cool air to be drawn into a house through vents strategically placed near to the ground.

gable ventilation

Untitled” by Wonderlane, CC BY

Jaali

Some Indian architecture makes use of a lattice screen called a jaali (or jali). The Jaali will often be placed lower to the ground to allow cool air to enter a room, and the lattice screen provides diffused light, while also providing privacy. They are quite beautiful as well.

jaali for ventilation

Jaali” by Nagarjan Kandukuru, CC BY

Windcatchers

Traditional Persian architecture often makes use of a structure known as a windcatcher (other names include shish-khan, a badgir, or a malqaf). When used effectively, windcatchers are able to cool a room enough to keep water at near freezing temperatures throughout the summer months. A windcatcher is a raised tower structure, typically on the roof of a building. It may have 4 or 8 sides, and has openings on 1, all 4, or all 8 sides, depending on typical air patterns in a location.   A windcatcher can work in three different ways. It can, as it’s name suggests, catch wind and direct it downwards into a room. It can also function as a solar chimney, allowing hot air to escape, cause a pressure gradient, and pull in cool air. In a climate that has a diurnal cycle – hot days and cold nights – this is especially useful. When paired with good building materials such as adobe, a windcatcher can keep the inside of a building quite cool. Thirdly, it can be paired with an underground canal. The windcatcher will pull warm air upwards, and with properly placed inlets, pull air in along the ground-cooled water. The water will cool the air, and the now cooled air will be pulled throughout the structure.

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Passive Cooling

There are a number of simple ways you can use passive design to keep your already constructed building cooler during the hot summer months, as well as some really cool building techniques that can be incorporated into construction to keep a building cool.  Today I’m going to cover the simple, already constructed building methods.

Awnings

Passive heating is all about trapping the heat from the sun inside your building. Likewise, passive cooling is about keeping that heat out. In the posts about passive lighting and passive heating, I talked about how important southern facing windows are to letting light and heat into a building, but what do you do with those windows during the summer? Using an awning on your southern windows can be a great solution. The angle of the awning will keep out the harsher rays of the sun in the summer, and in the winter, when the sun is angled lower in the sky, the light and heat will still be able to come in under the awning.

Shade Trees

Planting a deciduous shade tree in your southern yard can help keep your home or building cool as well. In the summer months, the leafy tree will provide shade for your southern windows, and if the tree is tall enough, for the roof as well.  In the winter, the tree will drop its leaves and let the light and heat pass through.

Curtains

Using thick curtains on southern and western facing window during the day can also keep keep a room or building cool by keeping the sun out, in the evening when the harshness of the rays have lessened, you can open the curtains again to let in the light.

Air Flow

Get that air moving. Open up windows on all sides of the building, and keep interior doors open as well to help allow the air to pass through the building.

Next week I’ll get into some of the ways that we can use construction to help get the air moving, and keep it cool in the first place.

Are you looking for an introduction to passive design? You can find it here.

Oh, hey, Building Earth has a facebook page now.  Keep up to date on posts and other interesting green news by liking us!

Passive Heating do-it-now

Ok, maybe you don’t have any big renovations planned for your home, but you still want to make your living space more heat energy efficient. Let’s go back to the second goal in passive heating:  Seal up your building so the heat doesn’t escape. Here are some simple things you can do to seal up your home and keep it warm without burning so much gas this winter.

Caulk

The thing about warm air is that it can escape through really tiny holes and cracks, so we want to do our best to fill them all in. Start by checking your windows, where the frame of the window comes in contact with the wooden sill. Is it sealed? If not, use caulk all the way around to fill in and block any potential leaks. Now look at the junction between the glass and the window frame and do the same. You can find clear caulk especially made for windows for this project.

Window Plastic

To add an extra layer of sealant, (or if you live in an apartment and can’t get permission to caulk your windows,) go with the old standby of window plastic. Wipe down the sill well, and make sure it is dry before putting down the double sided tape to help ensure a good seal.

Weather Stripping

Doors are the other prime leak location. Especially older wooden doors whose wood has begun to weather and warp. You can help stop up those possible leaks by putting weather stripping on the edges of the door. A draft guard along the bottom edge works well to block leaks too. Make sure you measure your door and the gaps between the door and the jam to ensure you get the appropriate size weather stripping and draft guard. You want the weather stripping to be slightly thicker than the gap it is filling to get a good seal. So there you have it, three simple ways to make your house better at passive heating. The great news is, these three things can also help keep your house cool during the summer as well. And we’ll have more on that coming up.

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Are you looking for an introduction to passive design? You can find it here.

Oh, hey, Building Earth has a facebook page now.  Keep up to date on posts and other interesting green news by liking us!