Image Credit: James R Salomon
Image Credit: Richard Renner Nearly 20 basic community resources and 6 open spaces can be found within a 1/2-mile radius of the project.
Image Credit: Richard Renner This photo of the original loft interior shows that the windowless side of the space was rather dark.
Image Credit: Richard Renner This view of the interior of the loft shows an inspection hole made near the ceiling to get a better understanding of the building’s structure.
Image Credit: Richard Renner During the demolition phase of the work, reusable materials (including structural materials) were set aside for salvage or recycling.
Image Credit: Richard Renner Demolition for a new side entry serving the living space above. Note the wythes of structural brick in the exterior wall.
Image Credit: Richard Renner Demolition of the perimeter of the slab to install drainage revealed that there were no footings under the structural brick exterior walls. The installation of new concrete footings under the existing wall was done in a leapfrog manner, alternating short sections, to maintain support for the wall.
Image Credit: Richard Renner The new framing was spaced off the exterior wall to include room for a drainage plane and spray foam insulation.
Image Credit: Richard Renner High-density spray foam (shown here in the roof monitor) was installed to create an air and thermal barrier.
Image Credit: Richard Renner A shot of the new loft looking south. Because of the new roof monitor and the light-colored flooring, the new space is bright and airy.
Image Credit: Peter Vanderwarker The second story apartment looking to the north.
Image Credit: Peter Vanderwarker The new study space is full of daylight. Note the open-panel kneewalls, which let light from the roof monitor penetrate into the living space below.
Image Credit: Peter Vanderwarker Steel window frame material was used to fashion several types of finished hardware for the project.
Image Credit: Peter Vanderwarker Accessible from the elevated study, the vegetated roof serves as a seasonal patio.
Image Credit: James R Salomon The Renner site plan showing all the vegetative roof spaces.
Image Credit: Richard Renner Original building section showing the two full story spaces and the storage space loft.
Image Credit: Richard Renner Floor plans for the original retail clothing store and 2nd story apartment.
Image Credit: Richard Renner The final floor plans showing the reconfiguration of the loft space into a home office space with the roof monitor for daylighting.
Image Credit: Richard Renner Final building section showing the innovative use of space for the loft study.
Image Credit: Richard Renner This Fine Homebuilding cross section shows the carefully detailed continuous air and thermal barrier.
Image Credit: Fine Homebuidling This energy graph shows the relationship between predicted, actual, and the Thousand Home Challenge energy use threshold.
Image Credit: Richard Renner This energy use summary shows how the modeled energy consumption compares to the actual first year consumption. 28 MMBtus total energy consumption is a very impressive total for this space.
Image Credit: Richard Renner
In Portland, Maine, a leading green architect walks the talk on his home and office, achieving LEED Platinum
Architect Richard Renner and his wife Janet Friskey, a graphic designer, wanted a commute in downtown Portland, Maine that involved just a flight of stairs. “We jumped at the opportunity to purchase an old clothing store with an apartment above,” says Richard.
That turned out to be the easy part. “Our goals for the first-floor office and residence loft were an efficient building envelope, plenty of daylighting to the interior, and open floor plans for both spaces. And while we were at it, make the loft a LEED for Homes Platinum gut rehab.”
The best laid plans for the foundation
Renner feels that green principles should touch every part of his projects, including the waste management plan. “I really wanted to only gut what we had to, not what we could. But right off the bat with the foundation, we ran into trouble,” admits Renner.
Careful excavation around the perimeter of the first floor slab to install perimeter drains revealed that the exterior walls lacked any footings. It turned out that both the slab and the walls were so uneven that the entire slab ended up in a dumpster. But Renner quickly adds, “While we ended up not being able to reuse the slab, it all ended up in a crusher for recycling.”
And Renner ended up capitalizing on this twist to his plans. “With the old slab out, we changed the floor level to add 11 more inches of height to the 1st floor, installed a gravity foundation drainage system, and installed sub-slab insulation as well as a capillary break between the soil and our floor system.”
A continuous air and thermal barrier for the building envelope
The first challenge in creating a high-performance envelope for this building is the brick exterior walls. “You have to lose that great brick look on one side or the other,” says Renner. “We decided to give up some precious floor space and get a new brighter surface on the interior by studding in walls to be filled with foam, spacing the stud walls 1 to 1.5 inches off the brick to eliminate thermal bridging and also allowing space for a drainage mat.”
New triple-glazed windows were installed flush to the interior in part to make the window installation detail simpler but also to keep alignment with the interior insulation and air barrier.
At the roof line, a combination insulation system was used: 2 inches of closed-cell foam as the air and vapor retarder with the rest of the 12-inch plus framing cavity filled with dense-packed cellulose. With the exterior brick walls air-sealed and insulated on the interior, it was easy to make the roof air and thermal barrier continuous with the wall system.
“We must have done it right — our blower-door test result came in at 2.39 ACH 50 (0.12 ACHnat),” Renner proudly states. “Not bad for a gut rehab.” Not bad, indeed.
NOTE: With this type of insulation approach — flash-and-fill — the relationship between the R-values of the foam and remaining cavity fill is important and affects the need for an interior vapor retarder and the potential for wintertime interstitial moisture accumulation. See these three GBA blogs:
- Vapor Profiles Help Predict Whether a Wall Can Dry);
- Are Dewpoint Calculations Really Necessary?;
- Calculating the Minimum Thickness of Rigid Foam Sheathing.
LEED Platinum and the Thousand Home Challenge
A HERS rating of 43 certainly helped quite a bit toward the LEED for Homes Platinum goal, but Renner was a bit disappointed in not meeting the Thousand Home Challenge. “Our actual first-year total energy use came in at about 28 MMBtu, and we needed to be at about 23 MMBtu for the Thousand Home Challenge under Option B (Option A in the THC is based on comparing pre- and post-retrofit actual total energy use while Option B is based on building- and climate-specific performance algorithms).”
One factor is that only two people are living in a space that could easily accommodate three occupants; there is a second full bedroom. Since the actual overall energy use is quite low, it is hard to think of anything dramatic that could have been done differently. (See images #19 and #20 in the image – Energy Use Bar Graph and Energy Use Summary.)
Elegantly green interior elements
There are a number of really fine interior touches in this Portland residence: a loft-within-a-loft work space (image gallery #11), interior hardware made from steel window frame cut-offs (image gallery #13), perforated interior kneewall screens that hide clutter but allow deeper light penetration (image gallery #11), solar tubes for a windowless bathroom (with city night light pollution meaning they work for more than just day time). “The interior layout and design was a team effort,” asserts Renner. “My wife and I did much of it together, but my staff also collaborated quite a bit.”
The Renners will walk the talk
The Renners know that even the most energy efficient design and construction require follow-up by the occupants. Here is the Renner energy “to-do” list:
1. Aggressively address passive (“vampire”) loads.
2. Closely coordinate heat-recovery ventilation with open windows in warmer months. When the windows are open, turn the system completely off.
3. Turn down the heat in the winter. Daily setback will not work well, because the system is radiant, but overall set points could be lower. Bedroom zone is currently set at 62 degrees; the rest of the loft is set at 65 degrees. Both could be reduced somewhat.
NOTE: Renner adds: “The heating component of overall energy use meets the Thousand Home Challenge goal; one could turn down the heat, but we have chosen not to do so. It is worth noting that the annual cost of heat and hot water is only $320. I track these costs using heating bills.”
4. Put coffee in a thermos instead of using the coffee maker’s heating element to keep the coffee warm.
5. The outside light at the front door is left on all night, because there is a graffiti problem in the neighborhood. Installing a motion sensor would reduce energy use. Renner is currently finding that he can keep this outdoor light off except when entertaining.
6. Install an exterior sunshade at the south-facing clerestory windows to reduce heat gain in the summer.
7. Use the roof deck for drying clothes when possible.
Renner is experimenting with running the HRV less frequently, and turning it off completely when the house is empty.
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Lessons Learned
Richard Renner is very forthcoming about what worked well and what did not on his projects. Here are his lessons learned on their Portland loft:
The high windows in the clerestory are only ten feet above the windows on the main level, but this is enough of a difference to create air flow for natural ventilation. These high windows deliver sufficient daylight on all but the darkest days. A shade, which was planned but omitted for budget reasons, would have reduced solar gain in the summer.
The bathroom has no windows, but Solartube skylights provide plenty of daylight.
An unexpected benefit of triple glazing is that the loft is quiet in spite of its urban location.
The loft’s open plan and long interior views make it feel larger than its actual size.
Locating the heat-recovery ventilator above the bathroom ceiling makes maintenance more difficult. However, there was no other place to put it.
Recessing the windows to maximize size and thermal efficiency required complicated head, jamb, and sill flashing. Snow frozen on the deep sill occasionally restricts the operation of the awning windows.
At today’s prices, the 1-kW grid-tied photovoltaic system is not cost-effective. The building geometry created a less-than-optimal collector orientation, and the adjacent building and nearby trees reduced the solar aperture.
If Renner had it to do over again, he would install an induction cooktop instead of the gas cooktop.
And here is a closing comment that Richard believes about all of his work: “There is no conflict between high levels of building performance and good design.”
For more information, see Richard Renner's Fine Homebuilding article on this project: "A Brick Rehab Meets LEED's Highest Standards."
General Specs and Team
| Location: | Portland, ME |
|---|---|
| Bedrooms: | 2 |
| Bathrooms: | 1 |
| Living Space: | 1600 |
| Additional Notes: | This space is a full floor of loft residence above an equivalent area of office space below. |
Design and Project Management: Richard Renner, Richard Renner Architects Design collaboration and interiors: Janet Friskey, Friskey Design Engineering: Becker Structural Engineering Petersen Engineers Marc Rosenbaum, Energysmiths Terry Brennan, Camroden Lighting: J&M Lighting Design Construction: Kolbert Building Millwork: Wright-Ryan Construction Interior finished metalwork: Jon Chalfant, Chalfant Design
Energy Specs
- R-54 roof
- R-34 above-grade walls
- Accurate-Dorwin triple-glazed windows (U-factor=0.15; SHGC=0.29)
- Tankless gas water heating (0.95 AFUE)
- Baxi Luna condensing boiler
- Ductless mini-split air conditioning (13 SEER)
- Energy Star fluorescent lighting & appliances
Water Efficiency
- Toto toilets
- low-flow faucets
- Delta low-flow showerhead
- GreenGrid roof trays
Indoor Air Quality
- Low or no-VOC paint throughout
- Formaldehyde-free plywood for cabinet structures
- RenewAire HRV
Green Materials and Resource Efficiency
Alternate Energy Utilization
1 kW PV system, grid-tied
Certification
USGBC LEED for Homes Platinum
4 Comments
Temp setting?
"Bedroom zone is currently set at 62 degrees; the rest of the loft is set at 65 degrees. Both could be reduced somewhat."
Is this a serious statement? I lose interest in an otherwise compelling efficiency story when I hear statements like this. Normal people don't live in 60 degree homes. And so this story loses a broader audience and therefore the chance at a broader impact. Ed Begley Jr. Is the minority.
Seriously?
My wife and I would love to wake up to a 62 degree bedroom. Try 40 degrees or bankruptcy. But that's why I read GBA, a man can dream...
Temp settings?
65 is, in fact, quite comfortable. I can sit near a window in a T-shirt and sweater and read comfortably. Because of the high levels of insulation, the triple-glazed windows, and tight envelope, 65 degrees feels quite comfortable, and I'm not unusually cold-tolerant. The bedroom is set a little cooler, because we like it that way. I have no desire to lower the temperatures further, because we like to be comfortable. And since the annual cost for heating and hot water is $320, I have no need to do so.
I completely agree that for green design and construction to be effective, it must work for everyone, not just the committed. That was one of the goals for this project. We have had many visitors, of all ages and environmental "persuasions", and none has complained about the temperature.
Aesthetics
I totally agree with you Renner that we shouldn't forget about design when instituting these building technologies. I really connect with the design of your loft rehab, similar taste indeed. Nicely Done!
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