Energy Systems

From day one, our goal was to build one of the best performing homes available in Denver.  And the results have been clear.  These homes have a HERS rating of 39 and 41 respectively, which means they are both about 60% better energy performers than the standard code house.  Our estimated monthly utility bill, based on a REMRATE energy model is $80 dollars per month. 

Some of the reasons why, are detailed below.  For more information, please feel free to contact us.

Building Drainage
One of the rising crises in the Housing Industry is the rise in “Construction Defect Litigation.”  Simply put, poorly built houses lead to unhappy homeowners.  That is why we reference the latest in sound building science when developing wall systems, and do not just build “what the code requires”.  Our wall system helps to shed water, seal the house, and prevent the build up of moisture in any wall cavities. 

How did we do?  Our building envelope has been tested to have a “Natural Air Changes per Hour” of 0.1.  That means that through all the small holes and gaps that exist in every home, our house exchanges the volume of air inside 2.4 times per 24 hour period.  The typical new construction house built to code, has NACH of about 0.3 (older homes are even higher), which means it will exchange the volume of air 7.2 times in a 24 hour period. 

This means our home is tight, which improves your comfort, and it saves energy.  But without performing the proper 3rd party verification tests to measure building performance, a developer or builder can never tell you how energy efficient their homes really are. 

Blower Door Test

Duct Blaster Test

Insulation
With a wall section that gives a R-27 insulation value, heating and cooling bills will be minimal.  This value is achieved because of our two part approach to thermal efficiency.  In the wall cavities, we use the Knauff ‘blown-in-blanket fiberglass insulation system, which leaves no air gaps, empty cavities, or loose insulation.  Coupled with exterior foam board insulation which gives an extra R-4 to the entire building, the R-rating is increased significantly. 

This two-fold approach to insulation provides a superior R value because of the ‘blanket’ affect of the foam board insulation.  Because it is applied to the exterior of the house, it covers all thermal bridges—columns or beams in the house that the insulation does not cover.  With today’s volatile energy market such a major cause of concern, this proven system makes sense. 

HVAC
No house can be efficient with out the right systems.  Our goal from day one was to couple energy efficiency with home comfort and quality of life.  By using a 92% efficient Trane furnace, with split zones between the main floor and 2nd floor, we are able to control the indoor environment with ease. 

These homes also feature HRV outdoor air exchangers, a system that brings fresh air into the house, but allows it to be tempered by stale air that is discharged from the house at the same time.  This means that you have fresh air, but it isn’t 30 degrees in January, or 95 degrees, in July.

In addition, a house with interior doors closed does not function properly, because it does not allow for appropriate air flow throughout the house.  That is why all our rooms have transfer grills, offset openings that allow air to move freely from closed rooms to open ones, but not sounds.  In addition, we have also added humidifiers, and electronic air filters, because we know that comfort is about more than just temperature, it’s about the quality of the air. 

Fan ventilation
Each bathroom is equipped with a 50cfm energy star broan low scone fan ventilator.  These fans are all operated by timed switches, so that you never have to worry about leaving them on.  They are also hidden, disguised as recessed lights where appropriate.  One thing that homeowners often know little about, is how important it is to get the moist air that is created every time we bathe or shower out of a house.  This moisture, especially in winter, can cause significant damage to any house, as it tries to work it’s way out.  Because of the timers, you can ensure that the moist air is exhausted, but you don’t have to worry about leaving the fan on.

Radiant
Because of the design of these homes, and the blended conditions between indoor and outdoor, we knew that a typical carpeted basement was not the answer.  Instead, we chose a modern, yet timeless finish of stained concrete. 

 This lead us to implement a radiant heat system into the basement slabs.  With R-7 insulating board below the slab, we are able to maintain a comfortable temperature with ease.  To take this a step further, the radiant slabs are heated entirely by the solar panels on top of the house.  That means free heat, that only uses the energy of a 60watt light bulb to run the pump. 

 To prove this point, 233 South Washington currently has the solar thermal system supplying heat to the radiant slab in the basement.  235 S Washington streets system is turned off.  The temperature difference between the basements is noticed immediately.  On top of that, 233 S Washington has a zero utility bill for February and March.  235 S Washington has cost about $50 per month to maintain a temperature of 65 degrees.  So putting the solar energy into the basement slab creates the effect of putting a heating pad under the house, with little impact on the bill (233’s gas usage is offset by the electrical generation of the pV array, thus leading to a zero bill, and a building credit with the utility company). 

Water
Water usage is something that all Coloradans understand.  But low-flow toilets, and low-flow faucets (both included), are just the beginning.  The A.O. Smith Water heater we selected has an efficiency rating of 90%, and can maintain an indefinite output of 3.5 gallons per minute.  Coupled with the solar thermal system, which uses the sun to preheat all hot water before it enters the water heater, the demands on the water heater are reduced significantly. 

The Taco D’MAND Hot water Recirculation System
Finally, these homes feature hot-water recirculation lines, but with an added feature that no one should live with out.  While recirculation lines are wonderful at reducing the waste of ‘warm up water’--the cold water you waste every morning waiting for the shower to get hot—they have had one major draw back.  You either have to set a timer and hope you never need hot water outside that schedule, or you have to let the pump always run. 

Thanks to the D’MAND system, every time you enter a bathroom, or when you press a button at the kitchen sink, the hot water is there.  The D’MAND system uses motion sensors to activate the recirculation pump, so simply walking into the room means that hot water will be ready.   The system is also smart, and senses if you are still in the room, and if the water is still hot.  If so, it does nothing, but if it senses more activity and the water has cooled, the pump will turn on again.

Electricity
These homes come complete with 2.1 Kilowatt solar photovoltaic systems, which supply an estimated 37% of the annual electrical demand of these homes .  Additionally, we have implemented the Energy Star Advanced Lighting Package to minimize electrical consumption.  The ALP includes many usage reducing measures, including Energy Star fans, fixtures, and bulbs.  The homes also feature timers on all bath fans, which are also energy star, so that no exhaust fans are left on unattended. 

Lutron Radio RA System
One of the added features of these homes, is the installation of a Lutron Radio RA System.  These systems allow for remote control of the corridor and exterior lights in the home, and is an easily expandable system for the homeowner. 

Recycled Materials and Content
Construction waste makes up approximately 20% of annual waste in the United States.  That is why we have endeavored to recycle as much as possible on these jobs sites.  From scraps of wood, to the metal banding and cardboard that is used for shipping everything from lumber to light bulbs, anything that could be recycled, has been.   We have even been able to donate some of our framing cuts offs, the extra lumber that inevitably comes from building homes, to Habitat for Humanity.  Additionally, the scrap drywall is now being used as a soil amendment for Colorado farmers. 

Environmentally Friendly Materials
Beyond construction waste, it is important to implement environmentally conscious materials into any construction project.  Our metal roofs are longer lasting, and energy star because of the heat they reflect. Our insulated walls are made from 30% post-consumer recycled content, so the things that make our houses feel more comfortable, also help the environment. 

Wash Park Green is located at: 233 & 235 S. Washington Street, Denver, CO

*Gold certification pending final USGBC approval. Third party testing to achieve Gold certification has been completed.
Photos copyright Frank Ooms photography.
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