Saturday 08/22/2009 – the scheduling and preparations are complete and the long anticipated design workshop is finally becoming reality. I have the energy model and an agenda – and most importantly – I have gathered a green team.
We started the day in the house with a quick inventory of the gutted basement and first floor. Because the house offered no comfortable or clean enough room in which to conduct the workshop, I had organized a meeting room one block north at Saint Agatha Catholic Academy.
Corbett Lundsford from the Green Team Group started the workshop session with a summary of the energy model results, providing us the foundation for the following discussions, which we had organized into the broad subject areas insulation, heating system, ventilation, and floor plan layout.
Insulation
The two key principles are super-insulated (high R-value) and airtight (elimination of leaks and drafts). Simple enough, isn’t it? To my surprise, this issue got us deep into rocket science. I will dedicate a post or two just to this subject – so stay tuned!
My research has pointed me to open cell and closed cell spray foam insulation. We discussed alternative materials, environmental impact, the objective of an airtight building envelope, R-value and point of diminishing returns, as well as moisture management in the masonry building shell.
The consensus that emerged was that spray foam insulation may not be the most economic option (ranging from $0.40 to $1.25 per board foot), but would allow us to effectively meet our insulation and air tightness goals in the building shell. Cellulose insulation, with a high recycled content, was suggested as an alternative for the basement and first floor ceiling, providing the needed insulation and sound attenuation.
Because we plan to install a new concrete floor in the basement, we discussed insulation under the new floor slab. With no insulation, the floor slab would provide a nice cooling mass during summer. It would, however, make heating rather inefficient. The final recommendation was to integrate insulation under the concrete slab. It would provide the right conditions for a radiant floor heating system, which leads us to the next topic.
Heating systems
Our preferred energy source for heating and domestic hot water is a solar hot water (SHW) system. The preferred heating method is radiant hot water, such as cast iron baseboard heaters. The green team was quick to educate us about the water temperature demand of hot water radiators (typically ranging from 150 to 180°F) and the capacity of a SHW system (typically ranging from 100 to 120°F). We have a 30 to 80°F temperature difference problem to solve!
Not only that, but the green team recommended a backup option to the SHW for those overcast and cold stretches. I would love to install a biomass furnace. The problem is that the best, cleanest and most efficient models are all European. The green team suggested a high efficiency condensing gas furnace instead. I could always switch to a biomass furnace once a clean and high efficiency model becomes available on the U.S. market.
With a temperature problem to solve and a need for a backup furnace, geothermal entered the discussion as an alternative to SHW. It could provide the energy needed for heating and domestic hot water. That said, I was concerned about the electricity demand by the pumps and condensers of a geothermal system, making our zero energy goal more challenging. Geothermal and SHW is something that will require more research and additional expertise.
Ventilation
Ever heard of sick building syndrome? That’s when a building does not get sufficiently ventilated, the air becomes stale and unpleasant and pollutants and toxicants start to accumulate. With our plans for a super-insulated and air tight building envelope, indoor air quality (IAQ) and proper ventilation becomes very important.
I was hoping for passive ventilation option to avoid ventilation duct work in the building. It would be difficult to integrate into the interior architecture without having it look ridiculous. I pressed the green team hard on passive ventilation, but had to concede that some duct work will be needed if we would like to use a heat recovery or energy recovery ventilator (ERV or HRV).
Basically, ERV and HRV are air-to-air heat exchangers, taking the energy from the exhaust air and transferring it to the unconditioned supply air. I now get the fresh air I need for ventilation at minimized energy loss. The tradeoff is that I need to have the supply and exhaust points at opposite ends of each floor. The green team’s recommendation was to consider lowering the ceiling by 6 inches (from 10 feet down to 9 ½ feet) and using the flat, rectangular ducts. Although cylindrical ducts would create less drag on the air flow, we’re making the esthetic choice to trade some flow for the ability to fit the duct work into the ceiling.
Floor plan layout
My idea was that after we had brainstormed and decided on heating and ventilation, we could look at the floor plan to determine what utilities should go where. Well, I had to table this discussion. The problem was that our MEP (Mechanical-Electrical-Plumbing) contact was a no show for the workshop. We had no one who had the engineering expertise to confirm the feasibility of our ideas or where to place and how to route utilities. Instead my research list grew and was to keep me busy for the next few weeks.
A big thank you…
… to our workshop green team:
- Howard Allen – Howard Allen Architects
- John Edel – Chicago Sustainable Manufacturing Center
- Ted Krasnesky – Pepper Construction
- David Lemaire – Hammerhead Carpentry, Inc.
- Corbett Lundsford – Dream Green Group LLC
- Drew Schmidt – student at Waubonsee Community College
- Mark Weitekamper – GreenWerks, Inc.
- Ryan Wilson – Conservation Design Forum, Inc.
