Energy Prices: How do they effect our cityscape

[cybertea]

Does anyone have any first hand experiences with energy prices and skyscrappers?

I can imagine it being a massive issue, considering how much energy a skyscrapper must require.

With the recent massive energy price hikes in Ontario, is this beginning to choke construction? Investment returns? Future projects?

I'm very curious, but no little on the subject.

 

[howl]

Higher density development is much more energy efficient than lower density development on a per unit basis so as energy prices increase I would expect to see more skyscrapers not fewer.

 

[Monarch Butterfly]

The higher the density, the more walking is involved. More walking, the less use of the automobile. More walking, the more exercise one gets, less doctor visits.

 

[spider]

The higher the density, the more walking is involved. More walking, the less use of the automobile. More walking, the more exercise one gets, less doctor visits.

all of these advantages are of course offset by a surge in shoe repair and replacement expenses.

I have to wonder if the density so often extolled as a virtue in city life is a reference to the housing or the housed?

 

[DarnDirtyApe]

Higher density development is much more energy efficient than lower density development on a per unit basis so as energy prices increase I would expect to see more skyscrapers not fewer.

The most efficient form of housing is that which maximizes the ratio of interior living space to outside walls. Point towers with glass cladding are relatively inefficient because of the small floor plate size, elevators, hallways, and large heat-loss/gain through the glass. I have seen stats on the energy effiency of different forms of housing, but wasn't able to find anything on google. However, the numbers show that a squat mid-rise building is typically most efficient - not surprising when you look at the built form of European cities that developed before the discovery of oil, or still subject to high energy costs.

 

[freshcutgrass]

The most efficient form of housing is that which maximizes the ratio of interior living space to outside walls. Point towers with glass cladding are relatively inefficient because of the small floor plate size, elevators, hallways, and large heat-loss/gain through the glass. I have seen stats on the energy effiency of different forms of housing, but wasn't able to find anything on google. However, the numbers show that a squat mid-rise building is typically most efficient - not surprising when you look at the built form of European cities that developed before the discovery of oil, or still subject to high energy costs.

In terms of heat loss, I don't see a lot of difference between a high-rise and a mid-rise building. Construction methods and materials designed to reduce heat loss will determine the major difference in heat loss. The interior space to exposed surface in any multi-unit apartment building will be fairly low, no matter how tall it is. Heat loss does not just come from exposed walls, but from floors and ceilings as well. Apartment units typically have one exposed wall and a corner unit will have two. Newer condo apartments tend to have narrow floorplans with small exposed walls. Because the building will act as a heat sink, interior walls, floors and ceilings can actually be sources of heat gain.

A detached, single family dwelling is the worse case scenario, as all four walls, plus ceilings & floors will be sources of heat loss.

In terms of low density vs high density, the cost of delivering that energy becomes a cost factor. The higher the density, the less distance that energy delivery system needs to travel.

 

[DarnDirtyApe]

It is just simple math that given two buildings with equal square footage, the one that is more like a cube while have a smaller surface area, and require less energy to heat and cool. There are more corner units in point towers than in a boxy building.

I do agree with you that materials are very important. Typically high-rise condos are cladded with curtain walls with lots of glass, which provide almost no r-value. With the exception of passive heat gain in winter or specialized applications (automated blind systems, etc.) windows generally kill energy efficiency.

Oh yeah, and you actually want thermal mass in the summer, as it evens out the internal temperature between the hottest part of the day and the cooler night. Again, more windows = more air conditioning.

The typical single-family house is an energy hog, but it is easier to build a net-zero single-family dwelling than a net-zero highrise because passive cooling and heating is easier on a small scale.

 

[freshcutgrass]

It is just simple math that given two buildings with equal square footage, the one that is more like a cube while have a smaller surface area, and require less energy to heat and cool. There are more corner units in point towers than in a boxy building.

On a unit-by-unit basis, it's gonna be about the same...a corner unit is a corner unit. And I'm not sure what your difference between a "boxy" building and a "point tower" is. The less exposed wall you have, the more of a bowling alley you are going to get...it's a bit of a diminishing return in terms of living space vs negligible energy savings. Hell...why not just move into an underground bunker? And more squat or rectilinear buildings tend to have much more hallways that need heating and cooling than point towers as well.

windows generally kill energy efficiency.

Who says a high-rise unit has any more windows than a mid-rise unit? It might...it might not.

Look....you're either using energy efficient design for your building envelope...or you're not.

The typical single-family house is an energy hog, but it is easier to build a net-zero single-family dwelling than a net-zero highrise because passive cooling and heating is easier on a small scale.

It isn't "easier" or "harder" at all. The only difference is, that for a detached, single family dwelling, it will cost more per unit to achieve it.

 

[Monarch Butterfly]

Consider the following, from Statistics Canada, at this link:

Energy prices rose 10.6% during the 12 months to February, after posting a 9.0% increase the previous month. Gasoline prices continued to increase in February, rising 15.7%, after recording a 13.0% increase in the 12 months to January.

The direction will be for less car use, if possible.

 

[DarnDirtyApe]

Imagine you have a bunch of 1 cm X 1 cm X 1 cm building blocks, and you make two buildings - one is 60 blocks high x 2 wide x 2 long, and the other is 15 x 8 x 2. Both contain 240 blocks, and in both cases all blocks have at least 1 face exposed to the outside.

Building A:
Surface area - 60 x 2 x 4 (four sides) + 2x2 (roof) = 484 cm^2 of exterior walls

Building B - 15x8 (wide sides) + 15x2 (narrow sides) + 2x8 (roof) = 166 cm^2 of exterior walls

Typical point tower floorplates will have more corner units as a proportion of the total, which means more heat loss. Check out the floorplans for Spire, for example:

http://www.simplycondos.com/condos/toronto/condos/Q_Z/spire.htm

More than half of the units are corner units, and the mechanical core takes up a significant chunk of the floorplate.

EDIT: Also, you are right that built form and materials used (glass curtain walls) are different issues, but my point was that curtain walls are not efficient.

You also need to compare apples to apples, so think in terms of energy consumption per square foot of living space, not by unit. Otherwise you're mixing up different effects, such as family size and size of living space preferences.

For a more obvious look at how energy prices will affect our cityscape, look to countries that already have high energy prices. They are building mid-rise energy-efficient housing, not point towers.

 

[freshcutgrass]

Imagine you have a bunch of 1 cm X 1 cm X 1 cm building blocks, and you make two buildings - one is 60 blocks high x 2 wide x 2 long, and the other is 15 x 8 x 2. Both contain 240 blocks, and in both cases all blocks have at least 1 face exposed to the outside.

Building A:
Surface area - 60 x 2 x 4 (four sides) + 2x2 (roof) = 484 cm^2 of exterior walls

Building B - 15x8 (wide sides) + 15x2 (narrow sides) + 2x8 (roof) = 166 cm^2 of exterior walls

Typical point tower floorplates will have more corner units as a proportion of the total, which means more heat loss. Check out the floorplans for Spire, for example:

http://www.simplycondos.com/condos/t.../Q_Z/spire.htm

More than half of the units are corner units, and the mechanical core takes up a significant chunk of the floorplate.

I don't need to "imagine" anything...all this theoretical math means nothing unless you can show the actual heat loss differences, which you haven't. And my point is there are other factors that weigh against theoretical heat loss differences between large and small floorplate buildings. I could also say that tall point towers are theoretically exposed to more high winds which will also affect heat loss...but so what. Any theoretical heat loss from this supposed disadvantage, will be made up in other areas where it provides an advantage. Any possible heat loss differences between floorplate sizes isn't the only factor in energy efficiencies building styles present. If there were any differences, it would be insignificant in the grand scheme.

I've spent enough years in the heating/cooling business to understand the bigger picture...I don't have to strictly rely on amateur armchair speculation. Seriously man, if you want to see what it all means, then look at an actual heat loss test done on a detached, single family dwelling and a condo unit. Look at the BTU numbers for both and then talk to me.

You also need to compare apples to apples, so think in terms of energy consumption per square foot of living space, not by unit. Otherwise you're mixing up different effects, such as family size and size of living space preferences.

I'm not mixing up anything. We can do it just as easily on a per square foot basis as well. We can do it on a per person basis too....it isn't going to make any difference...the detached, single family dwelling is going to be the least efficient in terms of heat loss. The condo unit does not have a roof...or a basement...or four (or more) walls, as many windows, no front doors, back doors, windows and garage doors opening all the time (which are huge heat loss points). The multi-unit building will have shared boilers for heating and and the same heat pump to perform air-to-water cooling. The detached, single family dwelling can have that type of system too, but it will be completely stand-alone, and less efficient to operate.

For a more obvious look at how energy prices will affect our cityscape, look to countries that already have high energy prices. They are building mid-rise energy-efficient housing, not point towers.

This isn't europe...we can't tear the city down and re-build Haussian Toronto. There are some places where point towers will serve an overall purpose better...and places where it won't. I'm not advocating one building style over another...just trying to be realistic rather than utopian about what we want to achieve. Nothing will hinge on any theory that point towers might represent some (probably insignificant) heat loss difference.