Sustainable Building Construction: Net Zero Energy

Showing posts with label Net Zero Energy. Show all posts

Tuesday, July 10, 2012

KEC Sustainable Details

It seems there are a few highlights to every high performance building or sustainable building project. However this project really takes advantage of sustainable design and construction in virtually every aspect of the project. As I look back on the blogs over the past 16 months, this aspect is lost in the details. So here is a recap of the sustainable details of the KEC.

The Net Zero Energy operation of the KEC is possible because all the energy required to run the facility in a year is generated onsite by an acre of photovoltaic panels (296kW array).

All walkway materials are reclaimed milled asphalt and lined with LED bollard lights activated by motion sensors to limit energy consumption.

Corridor walls are lined with tapped maple, salvaged from local sugar maple farms in VT.

Bathrooms are equipped with low flow Kohler plumbing fixtures to conserve water.

This shower head was specially engineered for this project. It provides low flow as standard pressure and has a push button for a brief surge of pressure which comes in handy when trying to rinse out the shampoo.

granite counters

Dorm room lights are all controlled with Lutron lighting control systems. Fan light and desk lamps are all switched by the door and are also tied into an occupancy sensor to turn off if nobody is in the room to conserve energy.

Windows are high performance argon filled double glazed Marvin units.

The cedar sunshade shades the southern exposure in summer while allowing winter sunlight in.

Exterior siding materials include FSC certified cedar and recycled content Certainteed cement board siding.

The controller for the Cinco Solar Evacuated Tubes allows you to evaluate your system needs and optimize your systems with the hot water produced by solar energy. It also allows you to monitor and program system performance.

Furniture selection also utilized reclaimed materials as you can see from this oak end table.

Locally sourced stone was used as a stone veneer feature on select elevations of the exterior.

Flow meters were installed which are integrated into the building dashboard. This will allow the end users to monitor and meter systems performance and usage.

Polished concrete floors were selected for corridors, labs, and the commons. This reduces material usage as tile, wood, or carpet will not be used in these spaces. The corridor classroom will pick up solar gain in the winter from southern exposure for passive heating.

Wednesday, May 30, 2012

KEC Passive Design

•

General Guidelines to Consider for Passive Design include:
Site conditions and solar orientation play a major role in siting a location. Consider the following:
– Natural vegetation
– Water run-off
– Seasonal water tables
– Solar orientation has a major effect on comfort and energy use
**note the image above was from an Australian website so for US, replace "north" with "south"

•Room layout should take into account how and when rooms will be used and how this impacts:
– Natural daylighting opportunities
– Natural ventilation opportunities
– Passive solar heating
– Sun shading, vegetative shading

•Orient the structure so south wall faces within 30 degrees of true south
- In rooms on S side, windows should equal 8-12% of floor area
- Shade S windows from summer sun
- Use casement windows on walls facing prevailing winds to scoop air for natural ventilation
- Locate rooms to take advantage of natural light and heat based on time of use

Use stormwater management such as peremeter drains, gutters, subsurface drains to address rainfall and groundwater

Glazing

- Keep in mind more glass equals less lighting
- South facing windows should have high solar heat gain to allow light in
- East and West windows should have low-gain to reject summer sun
- North windows should have lowest U-value

One of the primary goals of the KEC is to be a Net Zero Energy facility. All the energy used in a year must also be produced onsite. The energy source for the KEC is its PV array. Since the up front cost of PV is fairly expensive, the goal in designing the facility is to make it as efficient as possible. Therefore Passive Design techniques were used to reduce the energy consumption and up front PV costs.

The KEC implemented the following Passive Strategies:
- Building siting to optimize southern exposure
- High performance envelop - R44 walls and roof assemblies achieved with spray insulation and SIPS panels
- Shading with vegetation and sunshade to reject summer sun
- Natural ventilation with operable vents on the lower window units and on upper clerestories to draw air movement through the space as well as Earth Duct to pre-condition fresh outside air
- Thermal bridging - all exterior walls are double framed with an air space between framing

Monday, April 23, 2012

KEC Evacuated Tubes

Evacuated tubes manufactured by Cinco Solar will be used to make hot water on the roof of the KEC. This renewable energy source is part of the building's overall strategy to achieve LEED Platinum and Net Zero Energy. Lets take a look at how this system works.

The heat pipe is attached to the back of an absorber plate. Evaporator fluid is contained within the heat pipe. These components are housed within a vacuum sealed glass tube for maximum insulation and heat retention. Solar energy is transferred through the absorber plate and the heat pipe and into the evaporator fluid, converting it to vapor. The vapor rises to the condenser bulb at the top of the heat pipe. The condesnor bulb is connected to a manifold via a dry socket. Water is pumped through the manifold and absorbs heat through the dry socket. The condenser bulb releases the latent heat of evaporation in the water flowing through the manifold and the vapor condenses. The condensate returns to the bottom of the heat pipe and the cycle is repeated.

[sample photo]

The benefit of evacuated tubes over other types of solar hot water systems is they can be used in cold climates, they generate heat on cloudy days, and they can be used for space heating in addition to domestic hot water. They are typically more expensive than flat plate collectors.

Progress photos can be seen below:

Monday, March 12, 2012

KEC Solar PV

The ground mounted photovoltaic (PV) array is located just north of the building site, facing South for optimal performance conditions. It is a 296kW array and will produce all the energy consumed by the KEC over a year, making the facility Net-Zero Energy, which is expected to be 44.7 kBtu/sq ft annually. The array is connected to the grid and will produces more energy than needed in peak summer months, spinning the electric meter backwards. Then in the winter when solar production is lower the meter would spin forward drawing down on the account balance. The goal is at the end of any given year, the total energy produced and consumed on site balance out to zero.

Since PV is a fairly expensive up-front cost still, it is important to reduce the energy needs as much as possible. The KEC demonstrate a number of technologies to reduce energy needs including building siting, high performance building envelope, ground source heat pumps, earth duct, evacuated tubes, passive ventilation, and sun shading to name a few. Another key element is a commitment from the user group to accurately forecast the expected energy usage and adhere to these guidelines. This will be part of the living and learning experience for those at the KEC. Ultimately, the up front costs are offset by onsite energy production and the overall benefit to avoiding consumption of fossil fuels is a tremendous benefit.

Below are progress shots of the array being installed.