Sunday, July 13, 2014

Bad News for Home Depot Devotees in Denver

I had an estimator from Home Depot come to my office to bid a minisplit installation.  It was the same as calling ARS directly.  He said that all their installations, even for a small 9kbtu unit, start at $9,000 and go up from there.

Saturday, June 7, 2014

Is the "Sharing Economy" a Green Strategy for Denver?

When it comes to housing, airbnb is the most important player in the sharing economy.

Airbnb is a very useful tool to help a building owner eke more money out of his investment. More income means his investment is more sustainable.  The visitors and tourists that use his accommodation will spend money in the neighborhood. That makes the local businesses more sustainable.

Having thousands of airbnb hosts makes a growing city more sustainable because it means that fewer new hotels need to be built. New hotels place a large added burden on the utility infrastructure.

Some cities are resisting the new realities of the sharing economy, and are hampering its growth through unnecessary regulation.

For many years, Denver's zoning law has prohibited homeowners from having lease periods of less than 30 days.  This law has been challenged in Park Hill, but the law prevailed.

Today, Denver's neighborhood leaders tend to be the type of people that want to "preserve neighborhood character".   They do not like short term rentals.  City Council President Mary Beth Susman understands the "sharing economy" and has begun the discussion.   Stay tuned.

The Future of Residential Heat Recovery is Ductless

I just took ownership of the first ERV to be sold at Home Depot
Price $475
Extra stuff I learned about it once I got my hands on it:
1. The 16cfm mode, medium, (perfect for a 2 person bedroom) is only 0.3 sones at 4 watts. Almost inaudible.
2. Low speed is 8cfm (the one person setting) is 0.1 sones which is TOTALLY inaudible.
3. It can cycle on humidity if desired. That is, it will come on when the humidity reaches 45%RH (low), 55% (medium), or 65% (high). If the indoor humidity exceeds the set point, the unit is switched to high speed.  If the indoor humidity is within 5% of the set point, the unit operates at medium. If humidity is 5% below the set point, the unit switches to minimum speed.  This sounds like a reasonable control strategy for winter, but in the dry Mountain West, it would always be on low speed.  It sounds like the wrong control strategy for summer.
4. It pretty much is a ripoff of the Lunos design, but I don't know if either design is patented anyway.
It's not synchronized like the Lunos but I believe synchronization is unnecessary, and actually reduces the total house airflow.
5. The US distributor, Zoltan, will give a quantity discount, which gets it down to a price I can justify in new construction spec homes and rentals.  With a name like that, he knows all about predicting the future
6. The exterior vent cover is an elaborate, good looking, bomb proof fabrication of stainless steel.

7.  When the unit is off, it has a high quality, very tight powered plastic damper.

In my opinion, if the bedroom doors are left open except at bedtime, Fick's Law of Diffusion will ensure that fresh air will reach the rest of the house.   (The average speed of an air molecule flying around the room is 500m/s)  That means a three bedroom house may only need 3 total units.

Other important things that should be mentioned:
A.  Perfect zoning
B  Dead simple commissioning.
C.  Wires are easier to run than ducts.
D.  More total holes in the walls. (Bad)
E.  Inherent frost protection.

Tuesday, April 15, 2014

Car 2 Go Now Offering Regional Access

Called Moovel, now all North American car2go members can use the car2go service in any of car2go’s 13 cities across the U.S. and Canada:

Columbus, OH

Denver, CO
Portland OR
Austin TX
Washington DC
Southern Los Angeles area  CA
Toronto ONT
Miami FL
Vancouver BC
Seattle WA
Montreal, Quebec
Calgary, Alberta
San Diego CA

Expect a similar offering soon from Zipcar, Hertz 24/7 or similar company.  The convenience of Car2Go will erode their market share until they react.


Note - San Francisco is not covered, partly because of parking issues.  Apparently SF thinks that car sharing is less green than mass transit, even though one Car2Go can take 15-20 conventional cars off the street.


Tuesday, March 4, 2014

Clothes Dryer Efficiency Update- LG Releases Heat Pump Dryer for US Market

The holy grail of clothes drying technology is the heat pump condensing dryer (HPCD), and we are finally getting it.  If your family does a lot of laundry, this will pay for itself, even though it is pretty expensive at over $1500.

http://www.consumerreports.org/cro/news/2014/01/lg-s-new-dryer-saves-energy-and-money/index.htm

Consumer Reports neglects to mention the fact that there is no hole in the wall of your house.  Conventional dryers blow  heated air from the house to the outside in the winter, which effectively doubles their energy usage. This heat isn't measured in dryer tests, because the heat is provided by the house furnace.  So an HPCD actually uses four times less energy than a standard electric resistance dryer.  In addition, that hole in the wall can lose a significant amount of heat even when the dryer isn't running.

NOTE 7/13/14 - This new dryer from LG is not available yet.

Friday, February 7, 2014

The Great Ventilation Debate Rages On

The best minds in the building science field have not been able to yet agree on a ventilation rate for residential buildings.  The Energy Vanguard Blog is the best spot to witness that ongoing debate.

In my view, setting a standard for the ventilation rate is completely the wrong approach.  

As an analogy, consider the heating temperature control for a house.  If the temperature drops below a user-defined comfort setpoint, then heat is added to the space.  That's very simple, easy, cheap, and effective. Thermostatic control of  space heating can hardly be improved upon.  Why does it work so well?  Because it MEASURES, then CONTROLS.

In space heating, what we DON'T do is add a fixed number of btus per hour to the space during the winter season.  Yet that is what the ASHRAE or BSC ventilation standards propose to do*.  The current "cfm/person" approach is pseudoscience and should be abandoned in favor of  measurement and control.

What should we measure?  We're not sure yet, but if cost were no object, we would measure CO, CO2, methane, humidity, radon, and VOCs.  We may find one of these that can be a proxy for some of the others.

With that "air quality control" in place, the occupant can dial in a preferred setting, then forget about it.  The house will then get only what it needs, and there will be no money wasted on over-ventilation.

Ah, but we can't trust air-quality-ignorant occupants to know the best setting, right?  No, we can't, because many of the airborne contaminants cannot be detected by human sensory systems.  There is an obvious solution to that also, just ensure that the controls have scientifically derived maximum concentration settings for each contaminant.  Back to the space heating analogy:  thermostats have a minimum setting of 45F because bad things (freezing pipes) can happen below that setting.

*A standard ventilation rate can't account for all the variables.  Consider this:  what if the outdoor air is actually worse than the indoor air?  In that case, ventilation is the wrong answer, and a smart control would shut off the ventilation.

Tuesday, February 4, 2014

Living with Car2Go

Let's say you have a net zero energy home.  That's great.

But if you are still driving 20,000 miles a year, you are using way more energy than a carless person living in an old, energy-hog house.  So in order to live truly sustainably, you have to think outside of your box.

Cities are very energy efficient places to live, mainly because you can walk, ride a bike, or drive a very short distance for most things in your life.  Two of the most annoying things about living in a city are traffic, and finding a parking spot at your destination.  Therefore, city living becomes more enjoyable if you can live without a car.  As cities become more dense, cities must find ways to help their residents wean off of cars.

Real estate in cities is just too valuable to use for storing cars and for providing wide streets.  Since we only use our cars for 1-5% of the day, why are we paying to insure and store them the rest of the time?  Car2Go isn't a perfect solution yet, but it's an extremely convenient and successful way to help us share our cars and reduce the number of cars we need to store in the city.

Claire Martin of the Denver Post wrote a great article that describes the reality of using Car2Go, RTD and BikeShare rather than owning a car.