Archive for the ‘Renewable Energy’ Category

PHitW at Center of Renewable Energy Discussion

November 28th, 2013 by Tim Delhey Eian


The Pioneer Press, among other papers, recently posted this article about how Minnesota and other states grapple over value of home-grown solar electricity. To follow this discussion, or become active, check out these links:

The Pro Solar Collective

Midwest Energy article on the story

Hudson Star Observer article on the story (login required)




MRES Solar Tour 2011 to include Passive House in the Woods

September 16th, 2011 by Tim Delhey Eian

MRES Solar Tour 2011 logo

Minneapolis – The free, self-guided 16th Annual MRES Solar Tour Saturday, October 1, includes open houses at about 50 Minnesota homes, businesses and organizations that have solar and other renewable energy installations. Organized by the Minnesota Renewable Energy Society (MRES), the tour includes open houses in the Twin Cities and several other Minnesota communities from 10 a.m. to 5 p.m.

For the first time, this year the online guide to sites at will list each site’s additional eco-friendly features. Besides the usual pictures, maps and details about alternative energy technologies for each site, the guide will list eco-friendly features such as urban chickens, electric cars, rainwater storage systems and the like. Tour guests must register at to obtain addresses of the tour sites.

“The solar tour is popular with people who are thinking about purchasing some kind of renewable energy technology because it gives them a chance to see lots of systems and talk to lots of owners,” said Laura Cina, managing director of MRES. “The lists of other eco-friendly site features this year should draw even more people to the event.”

The owner, representatives from TE Studio, as well as representatives from Energy Concepts will be on site during the day to answer your questions.



Zero Energy

April 7th, 2011 by Tim Delhey Eian

The March electricity bill and meter readings show that the home was zero energy during the month. After a long and cloudy winter we are now observing surplus energy generation, which will offset the winter-use of electricity.

On a related note, the energy monitor is showing that the PV systems produce at near the nominal output they are rated. Over the last week we’ve seen 4.4kW and more out of the 4.68kW-rated arrays.

Meanwhile, we are on the quest for carbon-neutral operation. Again, with a very cloudy winter that yielded neither great passive solar heat gains, nor plentiful active solar electricity and hot water, we are excited to see all sources pick up now on the way to carbon neutral operation.


Power Plant Online [Update]

September 14th, 2010 by Tim Delhey Eian
Passive House in the Woods Photovoltaic Tracker

Photovoltaic Tracker

Passive Houes in the Woods, solar panels on the roof

Solar thermal panels on the roof

We are happy to announce that the solar photovoltaic system at the Passive House in the Woods produced the first 1/2 kWh of electricity yesterday. Both the solar electric and solar hot water systems will help this home achieve carbon-neutral operation and offset its footprint.

[Update] Midway through day 2 of operations, the PV system has now generated in excess of 50 kWh. It is exciting to see the power generation meter spin up and start to offset the consumption meter!


Mechanical Systems

May 28th, 2010 by Tim Delhey Eian

The building is currently in the “rough-in” stage, which means that electrical, plumbing, and mechanical systems are being installed.


Passive House in the Woods wiring

Wiring bundles

Passive House in the Woods electrical box

Electrical box

Both line and low voltage wiring are installed by EHS. They take great care in a clean installation that is easy to understand. Low voltage and line voltage lines are run in separate bundles in an effort to keep signals within undisturbed.

The electrical system in a Passive House is similar to ordinary electric systems with the exception that any protrusion through exterior walls or the roof are being sealed for air-tightness and uninterrupted insulation.

Gary chose to have a lighting control system by Lutron installed. This is not required by the Passive House standard but can help reduce lighting-related energy loads.


Passive House in the Woods, air admittance valve

Plumbing with air-admittance valve

Passive House in the Woods insulated water supply lines

Insulated water supply lines

Passive House in the Woods wall-hung toilet rough-in

Wall-hung toilet rough-in

The plumbing system is very simple. The design of the home puts most of it in one single wall that extends vertically from the basement to the second floor throughout the home. This means short waste and supply pipe runs, and an economical installation. The supply lines are copper, and continuously insulated for efficiency. The waste lines are PVC, and mostly insulated. Warm waste water is used to pre-warm the well-water that is being pumped into the hot water tank, upping the efficiency of the hot water system. Additionally, hot water is being pre-heated by a solar thermal collector on the roof. Last but not least, an electric on-demand water heater can boost the water temperature if the combination of waste-water heat recovery and solar thermal pre-heating do not make it hot enough. 85% of the hot water needs will not require the on-demand unit.

The plumbing system in a Passive House is similar to ordinary plumbing systems with the exception that pipe runs are continuously insulated, and that air-admittance valves are being used instead of vent stacks.


Passive House in the Woods ventilation system

Ventilation system (duct and ceiling box)

Passive House in the Woods Passive House certified Luefta ventilation machine

Passive House certified Lüfta ventilation machine

The ventilation system is at the heart of each Passive House. This building will utilize a Passive House certified Lüfta heat recovery ventilator from Germany, supplied by Peak Building Products. It will be combined with a 600 foot PEX earth loop provided by Rehau—buried below frost on the property. This system will pre-warm, or pre-cool and dehumidify the incoming ventilation air and boost the system’s efficiency to well above 90%. The Luefta machine will supply the entire home with outside air year-round, and exhaust air from the bathrooms and kitchen. The ductwork comes from Inno-Products and is comprised of a home-run layout with 3″ diameter plastic flex-ducts. The systems throughput is being adjusted by sensors that measure both CO2 and humidity levels in the air. This setup means that the homeowner does not have to adjust ventilation rates, and that the system will ramp down when it’s not needed to conserve energy.

Backup Heating

Nuheat standard mats, product image

Nuheat standard mats

Nuheat is supplying electric in-floor heating mats on room temperature thermostats. There are 7 zones throughout the home that can be individually adjusted. The entire system is sized to supply a peak heat load of 10 kBtu—about 3,000 Watts, or the equivalent of running 2 hair dryers at the same time. This represents a 90% reduction in heating system over most conventional construction today.

The heating system in a Passive House is very different from ordinary heating systems. It is merely a backup for long stretches of extremely cold and cloudy days in the winter and does not compare to conventional systems in terms of its capacity.

Renewable Systems

Passive House in the Woods PV tracker, underside

PV tracker, underside

Passive House in the Woods stand-offs for solar PV and thermal systems

Stand-offs for solar PV and thermal systems

Energy Concepts helped with the design of the renewable energy systems. There are three systems that will go into the building: A solar photovoltaic tracker, a photovoltaic panel array, and a solar thermal domestic hot water system. The photovoltaic systems are scheduled to produce about 6,750 kWh of electricity annually, while the solar thermal panel has the capability to pre warm enough domestic hot water to provide 85% of the annual demand. The remaining portion of heat needed will be supplied with the help of a Stiebel-Eltron booster heater.


Mini Series Part 4: Powered by Electricity?

May 13th, 2010 by Tim Delhey Eian

Yes, the Passive House in the Woods home is powered by electricity; and yes, electricity is predominantly a dirty fuel in this country—mostly generated by burning coal. However, electricity is a universal fuel that will likely prevail when other fuels become unfeasible. In addition, it can and is being generated in many different ways. Some of these options are NOT dirty at all and one of these cleaner options is photovoltaic power made with the help of solar panels.

Passive House in the Woods, footing for solar tracker

Pouring a footing for the solar tracker

PV Tracker

PV tracker similar to this project

Gary decided to use solar electricity and generate it on site with the help of a solar tracker as well as a Read on »


Solar Power

May 3rd, 2010 by Tim Delhey Eian

by Peter Henry, Energy Concepts

As sustainable design moves out of its infancy and tries to establish norms and standards for new construction, one of its central challenges is how to create energy that can power an entire house–and where possible–feed any surplus back to the grid.

Energy Concepts (ECI) was contacted early on as the Passive House in the Woods project concepts were being explored. As 2009 Focus on Energy Market Provider of the Year, ECIʼs veteran engineer Craig Tarr has the kind of experience and technical background to make a “carbon neutral” building become “carbon negative”–that is, a building that produces more energy than it consumes.

There is nothing more sustainable than creating a building that is a net producer of energy rather than a consumer. Given the problems of fossil fuel electricity production, this is likely to be the “gold standard” in sustainable design going forward. Quite simply: if we are not part of generating societyʼs solutions, than we are part of its problem; or at least, are certainly subject to its problems.

With that in mind, ECI set out to design a system that would meet a high standard: producing at least as much energy as it consumes. Read on »