June 11th, 2010•
Green Buildings•
When looking at the myriad components defining a sustainable home, operational efficiencies become key in realizing high performance building systems, which will minimize carbon footprint and cost of energy factors.
A zero energy building (ZEB) or net zero energy building is a general term applied to a building’s use with zero net energy consumption and zero carbon emissions annually. See Zero Energy Building on Wikipedia.
Two significant design factors for ZEB’s:
- Reduction of energy demand for a specific design.
- Supply the lowest impact/carbon neutral energy to the project.
The thought process regarding designs for ZEB’s evolve along the following lines:
- Need
- Location
- Passive Options
- Assisted Options
- Mechanicals
- Interactive Options (smart controls)
- Commissioning (multi-year process)
- Improvements (through logging home data and learning from this)
- Purchase Offsets (carbon) or implement renewable energy on site
Active Systems vs. Passive Designs:
Passive Solar heating design includes increasing temperature thresholds by 1 degree hotter and colder and a focus on night-time cooling options (assisted, if needed) with daylight harvesting tied in with smart controls for both heating and lighting. Solar chimneys may be incorporated in order to avoid the addition of mechanical cooling systems. Occupants will be linked closely with these passive systems in terms of heating and cooling (modifying existing behaviors), including the use of electricity (plug loads, etc.).
Some Systems that Apply:
Heat exchangers have become a design requirement in airtight buildings. These may take the form of HRV’s (north) ERV’s (south) and GFX thermal recovery systems for downpipes (hot water energy recovery).
Ground or water source heat pumps connected with hydronic heating systems may provide winter heating if site conditions allow (typically grid-tied only). Motors with ECM specifications should be utilized. See Brushless DC Electric Motor on Wikipedia.
LED lighting systems will allow substantial savings on energy and provide extremely durable service life. See Light Emitting Diode on Wikipedia.
Renewable Energy:
Renewable Energy may be utilized in off-grid or grid intertie applications. Solar Thermal systems should be incorporated into the design before Photovoltaic’s (PV), as payback is almost always superior. Wind energy in a hybrid system may be considered if site factors allow. Back-up generation will be required for all off-grid systems to augment battery power if the renewables fail. See Renewable Energy on Wikipedia.
Photo courtesy of ceibahamas.org
The purchase of carbon credits for energy and transportation of materials should be considered. Note that purchasing offsets or applying renewable energy is last on the list. Efficiencies in design, materials and passive/assisted systems are more highly weighted and important in a sustainable home than purchasing a large renewable energy system to make up for design/material inefficiencies.
Rating Systems:
There are currently a developing number of rating tools and systems on the market designed to help model and measure the performance a Net Zero home. They apply current and new best practices to ensure the building performance meets expectations, when newly commissioned and in years to come.
Models include:
PassivHaus
Building America Prototype
More models and rating tools are becoming available, worldwide, a trend that points to the growing acceptance of high performance buildings and a renewed demand by homeowners to make their homes a more comfortable, healthier and carbon neutral place to live.
June 5th, 2010•
Green Buildings•
Creating the plans for a Green Home is similar in many ways to the design and material specification process of a normal house. There are, however, some key differences in this process that begin very early on and require the homeowner to carefully review existing needs and wants and then apply them to a project that will, in essence, be smaller, more energy efficient, water conserving, durable and connected to the site.
Great – only positive synergies and absolutely no downside, right? Well, maybe…
The design process of a green home requires an integrated approach from the very beginning, one that includes the future occupant (you) and a team of specialists including the architect, engineers, contractor and material suppliers. You are now an integral part of the team and it may be somewhat daunting for many who don’t have this type of experience or are less inclined to become active in the process because of a perceived shortcoming in the skill-sets required. This is a situation we all face in our careers or chosen professions and when encountered, we dig deep into our life-long-learning bag of tricks and apply these principles to tackle the new challenge. Becoming an active and valuable part of an Integrated Design Team and working on something of paramount importance , your home, will become one of the most rewarding experiences of your life.
Lori Ryker, author of Off Grid Homes: Case Studies For Sustainable Living (2007, Gibbs Smith) says it very well:
“Homes are expressions of day-to-day experiences. They provide us with a place of refuge and memory making. From within our dwellings, our lives unfold and are invented, while personal beliefs are explored and expressed… Homes have the ability to express and embody an understanding of ourselves and our relationship to the world around us. They express who we are, who we want to be, and how we will be remembered.”
How can you take this idealistic and compelling view and distill it into a working knowledge of the principles needed to make it happen? By doing some homework…
For those who prefer to read books:
One of my favorite books, when it comes to home design, is by architect Sarah Susanka. The Not So Big House: A Blueprint for the Way We Really Live (1998, The Taunton Press) is a great primer in looking at what is normative in today’s homes, the areas we actually tend to utilize and how to look at design with a new set of criteria that allows us to create more intimate and connected spaces. Take the time and do some of the exercises she recommends – they will assist in rationalizing room and space requirements and help pin-point your needs vs. wants.
Another great all-around design primer is The Essential House Book: Getting Back to Basics by Terrence Conran (1994, Conran Octopus Ltd. Crown Publishers Inc.). This book looks at every aspect of home, from a sense of place through to understanding layout, materials and systems. A room-by-room approach allows for a very thorough and complete understanding of concepts and applications. The photos are great (albeit a little Europe-centric) yet I find I use it regularly as a reference tool when reviewing designs in order to establish the perfect balance.
Another great reference tome is The New Moderns: Architecture and Design for Living by Jonathan Glancey and Richard Bryant (1994 in paperback, SOMA Books, Bay Books and Tapes, Inc.). This book applies a similar approach to The Essential House Book but connects with a New Modernist design genre that fits well with smaller, more efficient, homes.
Lori Ryker’s book, (2007, Gibbs Smith), utilizes a case study format to describe both the active and passive systems that make up a sustainable home. Cases are taken from around the world and the book combines both technical references and extensive interior/exterior photography to provide the reader with current projects and leading-edge technologies. The chosen homes connect well with the sites and a truly vernacular feel is evident in the architecture.
For those who prefer online tools:
Dwell Magazine is an excellent resource for both material and design links related to sustainable homes.
Architectural Record is another vast site that connects with the official magazine of the AIA (American Institute of Architects). AR’s emphasis on residential designs and materials, along with critical review of these projects, allow the reader to build a stockpile of current and relevant images relating to their own home.
For those who are a bit more technically-minded:
The Green Building Advisor website has a large amount of current and useable information available in the form of blogs, technical articles and material/product specifications.
More technical yet, but with a truly North American perspective is the Building Science Corporation. This website connects readers with books on building systems, seminars, technical white papers and building envelope section drawings that are climate specific. Their focus on energy efficiency combined with enhanced Indoor Air Quality (IAQ) is timely and directly linked with the growing Green Building Movement.
These tools will help you connect at a level that will fortify the Integrated Team approach, allow you to become a more active design participant and take on a new level of ownership, well before the project becomes three-dimensional.
Enjoy the process, because it is the journey that defines who we are as individuals and feeds the creation of the environment we call home.