LEED for Homes Germany – A Case Study

LEED for Homes is a USGBC rating system aimed at single and multifamily residential housing development with the goal of creating energy efficient, healthy, sustainable homes. The rating system has struggled to capture a significant portion of the market, in both the U.S. and Europe. The problem in Europe is exasperated by the inconsistent building standards from country to country, and also by the limited number of Green Raters in the region, along with the total absence of local Providers. My business partner Marc Holt & I became interested in the Homes rating system after attending a Green Rater training last year. The training was held at the Barcelona, Spain at the offices of Green Living Projects http://www.greenlivingprojects.com/en  and was conducted by Active Energies, a U.S. LEED for Homes Provider.  http://www.activeenergies.com/

After completing the training and passing the Green Rater exam, we were optimistic about the opportunities to grow the rating system, specifically in Germany, but also throughout Europe. As we examined our local home market however, we found ourselves asking several questions. Would the LEED standard add any value to the already high home building standard? Would the average home owner/builder pay a premium for LEED certification?  How difficult would it be to apply the U.S. centric “Homes” program to the German market?

Long before the Green Rater training, Marc had started to develop plans for the construction of a new home for himself and his family. This offered the perfect opportunity for us to conduct a case study of the synergies and conflicts between local German building codes and LEED. The project broke ground in March of this year. The 2 story, 183 sqm, (1970 sqft), 3 bedroom, home is being built in Enkenbach-Alsenborn, (Kreis Kaiserslautern). It will be constructed using air entrained masonry block construction (Ytong low energy block) with a wood and clay tile roof. The project is being built on a 400 square meter site, giving it a density of 24.75 dwelling units (DU) per hectare (10 DU/acre) The preliminary HERS model has returned an index rating of 21%, which is 79% more energy efficient than the “standard” American home. The home will feature an 6.5 kW solar array and hydronic radiant floor heating throughout.  The landscaping will be drought tolerant & native, and can be irrigated using rain water captured by an onsite catchment system. The project is targeting LEED Gold, but has the potential to achieve platinum.

Over the coming months we will chronicle the problems encountered and solutions found, as well as propose possible strategies to make the standard a better fit for Europe.

One of the decisions that needed to be made early in the process was whether or not to build a radon abatement system into the home. LEED for Homes requires an abatement system when building in areas of high radon concentration (>4pCi/L). As this is a prerequisite, getting it wrong means no certification!
We were quite fortunate that the project was being built in Rhineland-Pfalz, as it is the State in Germany where the most extensive radon mapping has occurred. Looking over the data available online, we were able to determine that the project was in an area of relatively low radon concern; < 10kBq/m3. However the available mapping only showed radon level potential in the ground, not working levels in the interior air. One study very roughly correlated working levels and ground potential, at 1:500, but this could not be relied on as accurate in all situations. We also noticed that testing was primarily done on agricultural areas, and levels for the cities and towns appeared to be simply extrapolated. I addition to not knowing the actual radon levels, we also faced the challenge that the local home builder was not comfortable with installing the EPA AirPLUS radon abatement system. This is a deviation from typical base material used beneath the slab, and it was unclear know how this would affect the stability of the foundation. This of course could be determined, but it would require engineering analysis, which would add both time and cost to the project. Also any departure from the builder’s standard methods would have shifted the liability for slab related defects to the homeowner. The builder did mention that in the 30 years that they had been constructing homes in the area, only had one customer had ever requested radon abatement measures, which were achieved with a radon rated vapor barrier (Ampack Sisalex 871) beneath the slab. The decision was made to move forward without the abatement system and to test the home after construction to determine the working levels of radon. Although a risky strategy, given the ground level information available and the fact that the building codes in Germany require a tight building envelope, it seemed to be a relatively safe risk. In order to get an additional level of comfort with the decision, a home of similar construction in the area, just a couple hundred meters from the project site, was tested. The working levels came back at 60 Bq/m3 (< 2pCi/L), well below the range that would require an abatement system. We could have also performed an “in ground test” on the project site itself, which measures the exhalation rate in Bq/m2*h. Although there is no direct conversion from this measure to working levels of radon, it would have indicate if high levels of radon where present on the site. We will not know for sure if we made the correct decision until the project is complete and tested, which should occur before the end of 2017. Check this blog for updates!

Radon UPDATE October 2017:
Radon testing of the project home was conducted in October 2017. A test kit was ordered from Environmental Analysis and placed in a room on the lower level of the house. The test canister was left exposed to the air in the space for 3 days and then returned to the manufacturer for analysis. The results returned indicated that the radon levels were well below the threshold that would require mitigation measures.
The radon content of the air was measured at: 30 Bq/m3 (0.81 pCi/L) +/- 20%

Mid-Construction Visit:
Sorry for the rather clinical, report style of writing, these inspection visit posts have taken on. First, it is the nature of these visits that one must methodically progress through a checklist of items, taking note of what is correct, and what requires additional attention. Secondly, I came to terms a long time ago with the fact that I’m not much of a story teller…so here are, just the facts….
The inspection began with a tour of the local area, noting location of bus and rail stops, as well as verifying open space requirements had been meet by a future local park. Also the number, type and location of shops, schools, and services, relative to the project home were, also verified. A question did arise regarding access to bike routes. It was explained that the speed limit on the street in the town of Enkenbach-Aselborn are mostly 30 KPH. In Germany it is assumed that bicycles can safely share the road were the speed are limited to 30 KPH or less, so marked/designated bike lanes are not needed.
Typically the mid construction inspection is schedule once the air barrier is complete and the installation is exposed, however in the case of Ytong structure the block acts as both air barrier and insulation. It was noted that in some location daylight could be seem between the blocks however as the exterior and interior plaster had yet to be applied, these minor discontinuities in the air barrier were deemed acceptable. Additional information is needed however about the exterior plaster system, as well as an understanding of how any damage or cracking of the finish will be addressed to prevent water infiltration into the Ytong block. The windows and exterior doors had been installed, as had the roof air barrier and tile, however the roof insulation was not in place. The builder stated that the insulation would not be installed until after the drying out period for the concrete topping slab, which h will encase the subfloor heating coils. Inspection of the roof insulation will require an additional visit by the Green Rater, as it will not be visible at the final construction visit. All domestic water and heating piping had been roughed in so it was simple to verify that he maximum hot water piping run distance were within the required limits. Utility penetration through the foundation slab were adequately seals against pest infiltration
There was a discussion with the homeowner and builder regarding the completion require Energy Star forms; Water Management Checklist and HVAC Design Report. The Water Management Checklist appears to be more applicable to wood frame construction. Although there are some footnotes regarding block construction, the feeling is much of the form does not apply to the Ytong systems. Further discussion will be had to try and decide the best way to complete this form. The HVAC Design Report is also of concern, primarily as the HVAC consultant has performed his calculation based on German /EU codes and I not familiar with AHRAE or English. Translating the form would help, however there are still could be areas where the codes do not agree. Additional discussions with the project team, verification team and possibly the USGBC will be need going forwards to resolve these challenges.
An inspection of the exterior revealed that erosion control measures were in place, including silt fencing along the boundary fence and protection of onsite manhole covers. Also the rough grading was done as to direct water away from the house foundations. A better understanding of the storm water control system is needed. The house, by local code, has an onsite cistern that will hold storm water runoff and slowly release it. However there seems to be some disagreement as to whether the water is released back into a combined sanitary/storm water system, or diverted to designated areas and allowed to absorb into the ground. The homeowner is also investigating using this water as part of a grey water system. . The Photo voltaic panels were installed on the roof in the orientation indicated on the project plans; verification of the size of the system and pitch of the roof will be needed to complete the HERS model and final submission package.
Radon testing of the property will not will possible until the interior plaster, roof insulation are complete. The project team anticipates being able to test the house sometime in the late summer (2017)

Blower Door Testing
Typically the blower door test will be performed in conjunction with the final construction inspection. In the case of the project house the builder provided testing as part of their package price; unfortunately it was not possible to find a date that worked for both the blower door test and the final inspection. The blower door testing was conducted on November 10, 2017. The test engineer set up his equipment and proceeded to tape over the exhaust vents in the bathrooms. This is allowable for per the DIN EN 13829 test standards, however LEED for Home requires that the vents be left uncovered. The test engineer agreed to perform the test both uncovered and covered. During the testing the engineer observed a couple of locations of possible air leaks using an infrared camera. At the NE and NW corners of the home, the windows wrap around the corners. A structural steel post had been inserted at each corner to support the glazing and add rigidity to the structure. It was between the steel post and windows were air leakage was observed. The builder, who was in in attendance for the testing, indicated that the areas would be caulk to stop the leaks. Despite the observed leaks, and not taping over the exhaust vents, the home exceeded the requirements of DIN EN 13829 (n50 = 1,5 1/h); the total leakage was measured as n50 = 1,3 1/h

Final Construction Visit
It had been hoped that the final construction inspection could have been scheduled prior to the homeowners moving into the property, however that was not possible. At the time of inspection, January 10, 2018, the family had occupied the house for approximately 3 months.
Inspection of the exterior revealed that the landscaping in place, and was consistent with the landscape plan proved by the project team. Although not fully established, the plantings nearest the house were set back the required distance from the foundations. The project team will need to document that the plants used are non-invasive species. The finish landscape and hardscape was sloped to directed water away from the home. The plaster finish on the exterior walls was complete and free of cracks or other penetrations. Photographs of all elevations were taken and will be included in the final submittal package.
Inside the home’s primary entrance there was a large space dedicated to shoe removal and storage. The flooring in the area, as throughout the house, was ceramic tile. CO detectors were observed installed on both levels of the home. The detectors were not hard wires, but were of the 10 year battery type.
Inspection of the mechanical room revealed that the water heater/storage tank where installed with a drain pan and the pans were piped to the sanitary sewer system. The domestic water pressure gauge read just under 4 bar. The floor of the laundry room was sloped towards a central floor drain. Photos of the manufacture’s label on the washing machine were taken to be compared to product data provided by the project team. A condensing clothes dryer was observed in the laundry room, so there was no need for the machine to be vented to the outside. No combustion appliances were observed; hot water heating and cooking appliances were all electric. The home had no fireplace or fossil fuel burning stoves.
A total of 3 bedroom were observed in additional to a large open plan living/kitchen area. The home also had 2 bathrooms, one on each level. The exhaust fan in the bathrooms operated continuously to meet the whole house ventilation requirement. Verification of fan CFM and homeowner override controls will be provided by the project team. The kitchen had a large exhaust hood that vented to the outside. This fan will also need to undergo operational testing to verify the rated CFM. This testing will be scheduled as some as possible. Photographs were taken of all appliances and fixtures and will be compared to the product data provided by the project team.
The homeowner showed the verification team the homeowner’s manual provided by the builder; the 3-ring binder included information regarding the homes systems and finishes.

The Submittal Process
As we enter the certification submittal stage of the process, the Project Team has encountered some challenges in documentation. Some issues were unforeseen, while others had been discussed with the contractor early in the design process, but apparently not clearly understood.
The trouble with trash….. The Construction Waste Management credit can be difficult to achieve in the U.S. simply because the sheer volume of waste generated by wood frame construction; generally the waste allowance is used up before the sheetrock arrives on the project. In Germany the Project Team felt they had a much better chance of achieving 2 or 3 points in this category since the construction practices tend to minimize waste. First, the Ytong block construction generated very little waste, all of which was sent back to the supplier. The wood structural members for the roof were all cut to size before being delivered to the jobsite, eliminating the majority of possible wood waste. The finished interior surfaces were plaster applied to the Ytong, so no drywall, and the flooring was a combination of wood laminate and ceramic tile, which also resulted in small amounts of left over scraps. In order to comply with the credit documentation the general contractor was paid to document waste removed from the project. The Project Team receive a combination of weight & volume tags showing waste, but only that generated from the start of the project through mechanical/electrical rough in. As the subcontractors working on finishes and installing systems were responsible for removing their own debris at the end of each day, none of this waste was tracked by the general contractor, thus creating a gap in documentation. The kitchen cabinetry and appliances were purchase directly from IKEA by the homeowner, who also installed them; this is pretty typical practice in Germany. There was waste generated by this process; primarily packaging in the form of cardboard, plastic, styrofoam, etc. All these materials were recycled by the homeowner through the city’s residential trash collection/curbside recycling program, creating another unknown.
When it came time to document the credit, it could be demonstrated from the few weight tags that existed that 1750kg of debris was removed from the site. As the baseline trash allowance for the project was 4190kg, the Project Team was fairly confident that even with the undocumented trash, the project was below the baseline level. In order to demonstrate compliance, the Project Team created a spreadsheet showing both the documented and estimated trash. For the flooring waste, a letter was obtained from the subcontractor stating the percentage of total flooring that was scrap. This was supplemented with photographs taken by the project team during the flooring installation. For the kitchen packaging waste, the IKEA website provided information about the dimensions of all the packaged components that comprised the kitchen. From this an estimated the cardboard and Styrofoam waste could be made, again supplemented by photos taken during the kitchen installation work. For work activities for which only photographs existed, reasonable assumptions of waste items such as grout bags, caulking tubes, paint buckets, misc. packaging, etc., were made. The spreadsheet, along with supporting documentation; waste tags, photographs, packaging calculations, and subcontractor letters, were packaged together with a narrative explaining both the documentation process and the waste disposal culture in Germany. In total, the project is estimated to have generated less than half (approx. 1800kg) the baseline allowance.
The documentation was submitted to the Homes Provider, for review, in September 2018. If the Provider feels the Project Team has made a strong enough argument, it will then be presented to the GBCI for consideration.