Active House – the “building that gives more than it takes “
There are a few green building standards competing for the industry’s attention in the US: USGBC’s LEED, the Green Building Initiative’s Green Globes, the International Living Future Institute’s Living building challenge, the Passive House (aka Passivhaus). And now, there is also the Active house.
Active Houses is energy efficient and uses only renewable resources. The indoor climate of the Active House is designed to be comfortable and healthy, and the home itself is designed to interact positively with the local environment.
Active House is a very new concept, it was first conceived in 2011, at a conference in Brussels, although the movement itself started in Copenhagen, Denmark. Since then, quite a few Active Houses were built in Europe. And just this year, the first two prototype houses were built in North America, one in the US, and one in Canada.
Active House key principles are:
Energy:
- a building that is energy efficient and easy to operate
- a building that substantially exceeds the statutory minimum in terms of energy efficiency
- a building that exploits a variety of renewable energy sources integrated in the overall design
Environment :
- a building that exerts the minimum impact on environmental and cultural resources
- a building that avoids ecological damage
- a building that is constructed of materials with focus on re-use.
Comfort:
- a building with an indoor climate that promotes health, comfort and sense of well-being
- a building that ensures good indoor air quality, adequate thermal climate and appropriate visual and acoustical comfort
- a building with an indoor climate that is easy for occupants to control and at the same time encourages responsible environmental behavior
The Active House concept is promoted by the Active House Alliance, which is a non-profit association registered in Belgium. The Alliance’s ambition is to create a “viable, independent and internationally influential principle for new buildings which would provide healthier and more comfortable lives for their residents without impacting negatively on the climate and the environment”.
The Active House Alliance issues the Principles, the Specificaiton and the Guidelines to help design teams to meet the Active House standards.
The Principles provides an overview of the vision, thinking and principles behind an Active House.
The Specification provides the insight and knowledge for the technical specifications and design concept for an Active House. The Specification is process-oriented and provides guidance on how to achieve the performance levels described in the technical specifications. It also gives some advice on the holistic approach to the design process (biodiversity, local culture and location). The specification, now in its 2nd edition, is comprised of the shared knowledge and experience of the Members of the Alliance, using an open source model.
The Guidelines address the process of planning the construction of an Active House.
Case Study – Active House USA
The very first Active House in the US was just finished in Webster Groves, MO. Webster Groves is located in a mixed humid climate region. A house built there has to meet both warm and cold climate efficiency needs, making it the ideal location for a prototype house.
Most Active Houses built in Europe showcase modern designs. However, because the Active House USA is located in a historic part of town, it was designed to “blend harmoniously with the historic homes in the surrounding area so it has the look and all the charm but outperforms them by far”. Although the house represents top of the line construction technology, it is still appraised on point for the average new home construction in this highly coveted, historic neighborhood of Webster Groves, MO.
Active House USA was designed using the Active House Specifications developed by the Active House Alliance and built for certification in four North American Sustainable building standards: Energy Star, EPA Indoor, Building America Builder’s Challenge, and ANSI ICC-700 (aka The National Green Building Standard). By meeting and exceeding these existing metrics and certifications, the Active House USA prototype aims to prove itself and to help develop standards for future Active Houses in North America.
Since this is the prototype, the homeowner has agreed to allow the University of Missouri’s Center for Sustainable Energy to monitor energy consumption and indoor air quality for the first year of residence. The research team will analyze the data and share it with the Belgium-based Active House Alliance and their UK-based contract-engineering firm, Grontmij, who will do the final commissioning of this Active House prototype. The data and information will also be shared with the NAHB’s Home Innovation Research Center, the certifying body for the ANSI ICC-70 standard.
On March 8 and 9, 2013 the final open house for Active House USA was held. Close to 2,000 people (!) came on these two days to see the house and to speak directly with the design and construction team.
Key Principles: Energy – Environment – Comfort
The stated goal of the design team was: “… to provide the homeowner with a cost-effective, and easy to operate and maintain living space, that creates a healthier and more comfortable lives for their occupants without impacting the climate.”
Throughout all phases of design and construction, the Active House USA design team specified energy efficient materials, design techniques and building practices with emphasis on renewable resources.
Active House USA is a very healthy house. It takes advantage of solar orientation, natural cross-ventilation and natural lighting in every room.
Solar orientation* in particular, was a key to successful performance planning for the Active House USA. A well-designed and properly oriented house capitalizes on solar heat gain in the winter and deflects unwanted heat in the summer. This simple consideration can significantly reduce a house’s energy use, it is free and will last for the entire life of the building. Proper solar orientation can also provide glare-free natural light throughout the house.
*Solar orientation refers to orienting the design of the house in relation to the natural path of the sun.
The interior layout of the house is open and airy, which will maximize daylight throughout the house. The house makes extensive use of vertical light, using sun tunnels and skylights, which makes daylighting even more effective as it provides a higher percentage of light with less glare. American architects worked with the engineers from the Active House Network in Denmark to maximize the effectiveness of the lighting design.
As a result, there is less need for artificial lighting, thus lower energy costs. Furthermore, less artificial lighting generates less heat, which in turn further decreases the demand for air conditioning in summer.
Issues with the Active House standard
Without a doubt, the Active House USA is a very important project for the green building movement in the US. However, some in the design community expressed reservations about certain green design claims of the Active House.
A look at Active Houses built to date, shows beautiful homes with a lot of skylights and windows. The problem is that a lot of windows and skylights greatly reduces the overall performance of the building envelope. The level of wall insulation in the Active House USA is barely above building code for the northern parts of the country (R-25 for walls, and R-45 for roof).
As far as the fully renewable energy goal, the Active House USA has solar panels on the roof, however, the other source of energy is gas. The gas heating is described as “a clean, low cost, domestic energy source, which provides an opportunity to broaden energy resources for the customer”. Still, many would say that this is greenwashing, and that the use of gas does not qualify the house to be called Net Zero energy.
Nevertheless, Active House has the potential to become a popular way of building, as it is much healthier and energy efficient than conventional homes.
