HRES Solar Thermal

On Friday, Andrea Ruedy Trimble, Jessica Parks, Carol Healy, Zhen Wu, Mitch Hunter, and Fady Ghattas of the Harvard Office for Sustainability took a tour of the solar thermal installations on 472-474 Broadway and 20-20a Prescott Streets in Cambridge. Bjorn Storz of Harvard Real Estate Services lead the tour. There are 14 flat plate collectors on the two roofs and they are expected to provide 30 to 40% of the domestic water demand. The solar planels collect heat through a glycol loop which is pumpted to plate frame heat exchangers in the basements. From there a water loop transfers heat to storage tanks. Finally, another set of plate fram heat exchangers transfers the heat to pre-heat the domestic water, which receives additioanl heating from natural gas boilers. The installation is expected to reduce GHG emissions by 13 MTCDE per year and save 2,300 therms of natural gas.

The systems performance is being tracked real time and available on the web. The public is invited to track the performance of the system by visiting http://harvard_prescott.heizwerk.at/ and logging in with username "frei" and password "frei". Solid Solar, the manufacturers, are continuing to monitor the system from Germany and making slight tweeks to the controls to optimize its performance.

Everybody on the Office for Sustainability staff enjoyed the tour and hopes to see more such installations on roofs around Harvard and elsewhere.

Read more.

Wasted Energy or Hospitality?

On Friday, we stayed at the Royal Sonesta in Cambridge, MA. The hotel is relatively nice with a great location right on the Charles River overlooking Boston, just a short walk to the Garden / North Station where we watched the Boston Celtics lose to the Orlando Magic (Boston was 2 for 19 from the 3 point line - ouch). When opening the door to our rooms (we had a large suite and a standard twin room that were connected), we were greeted by electric light. Lots and lots of electric light. In fact, there were at least 8 lights on between the two rooms. Each was controlled by a separate switch and had obviously been on for some time awaiting our arrival. We were just stopping by to drop off our bags and then walk to the Celtics game so I quickly made the rounds and made sure to shut off every one before leaving.


After the game we returned to our hotel room shocked to find it equally well lit as when we first arrived. This time I counted and there were definitely 8 separate lights turned on between the two rooms. It seems that in the three hours we were gone, somebody had come into the room just to put chocolates on our pillow and to turn on the lights. It was as if they had each room separately metered and immediately sent somebody up to turn on the lights the second the electricity demand dropped below 100 watts in any room. I called the front desk to ask why our lights were on and was told that it is their policy to do this every time somebody goes into a room, be it to clean up or just to drop off some chocolates. At my request they would not be turning on my lights for the remainder of our stay.


Admittedly, the lights were all compact fluorescents, but this gesture seems disingenuous when the hotel admits keeping lights on at all times is company policy. It also seems at odds with their "Passion for the Environment" signage in the bathroom.

Water Savings Calculations

Question sent by email:

I've heard you say you can save 40% of domestic water without any added cost. How do you do this? Is it use of gray water for flushing in addition to waterless urinals, low flow toilets, aerators on sinks, etc???

Response:

It was very easy to do in the past with fixture selection. The water efficient fixtures we use have no added cost compared to conventional fixtures. We could save a tiny bit more with gravity fed toilets (the kind with the tank like you have at home), but we usually use flushometer toilets (the more commercial kind with the silver pipes sticking out of the wall).

Lets look at the calculations assuming there are two people in the building, one man and one woman.

Base Case (code compliant)

Toilet = 1.6 gpf - 3 times/day for woman, 1 time for man

Urinal = 1.0 gpf - 0 times/day for woman, 2 times for man

Sink = 2.5 gpm @ 80 psi - 3 times/day for 25 seconds for everybody

Shower = 2.5 gpm @ 80 psi - 1 times/day for 5 minutes for 10% of people

Design Case (what we do)

Toilet = 1.6 / 1.1 gpf dual flush - 1 full 2 half times/day for woman, 1 full for man

Urinal = 0 gpf - 0 times/day for woman, 2 times for man

Sink = 0.5 gpm @ 80 psi - 3 times/day for 20 seconds (sensors) for everybody

Shower = 1.6 gpm @ 80 psi - 1 time/day for 5 minutes for 10% of people

The scenario above would save 48.1% of the water in an office setting based on a comparison to EPAct 1992 (calculation for LEED NC v2.2):

Now we usually get a little less credit for the same water usage because the base case for commercial sinks has been reduced to 0.5 gpm @ 60 psi.

Base Case (code compliant)

Toilet = 1.6 gpf - 3 times/day for woman, 1 time for man

Urinal = 1.0 gpf - 0 times/day for woman, 2 times for man

Sink = 0.5 gpm @ 60 psi - 3 times/day for 25 seconds for everybody

Shower = 2.5 gpm @ 80 psi - 1 times/day for 5 minutes for 10% of people

Design Case (what we do)

Toilet = 1.6 / 1.1 gpf dual flush - 1 full 2 half times/day for woman, 1 full for man

Urinal = 0 gpf - 0 times/day for woman, 2 times for man

Sink = 0.5 gpm @ 80 psi - 3 times/day for 20 seconds (sensors) for everybody

Shower = 1.6 gpm @ 80 psi - 1 time/day for 5 minutes for 10% of people

The scenario above would save 34.8% of the water in an office setting based on a comparison to EPAct 1992 and the new commercial fixture rules (calculation for LEED 2009). Of course there is no kitchen sink in this example (assuming a college dorm), but that would have to be added in if appropriate:

Residential buildings code still allows 2.5 gpm sinks, so we typically save 38.1% in old and new versions of LEED.

Base Case (code compliant)

Toilet = 1.6 gpf - 5 flushes/day for all

Sink = 0.5 gpm @ 60 psi - 5 times/day for 25 seconds

Shower = 2.5 gpm @ 80 psi - 1 time/day for 5 minutes

Design Case (what we do)

Toilet = 1.6 / 1.1 gpf dual flush - 1 full & 4 half flushes/day for all

Sink = 0.5 gpm @ 80 psi - 5 times/day for 25 seconds

Shower = 1.6 gpm @ 80 psi - 1 times/day for 5 minutes

Of course the calculations above are done for 2 people, but the percent reduction will remain the same regardless of the number of people as long as you assume a 50/50 split between men and women.

We have plans to use greywater in some buildings and one of my projects in South Carolina did this (see Half Moon Outfitters case study). Showers really drive the numbers in residential buildings and it is possible to go below 1.6 gpm. We usually use Delta H20 Kinetic showers, but many of the best low-flow showers aren't allowed in Massachusetts because they're not on the approved plumbing list. The toilet in the top right is a tank-type dual flush from Dubai. The urinal on the bottom left uses no water for flushing and has a trap that can be cleaned and refilled with oil (Kohler Steward).

Hope this helps.

Soldiers Field Park Wind Turbines

On September 22, Harvard Real Estate Services installed two 10-kilowatt Bergey Excel wind turbines on the top deck of the Soldiers Field Park Garage. We were on-hand to witness the installation and talked with the project manager (Chris Packard of JLL) and contractor (Tom Dowd of North Shore Solar and Wind Power). The turbines atop their 40 foot towers look great and are noticeable from a large part of Allston and Cambridge. The poles are mounted to steel supports that go through the top deck and down two more floors. The turbines automatically track the wind and are set to veer away from the wind if it is too high. The garage was recently retrofitted (project managed by our group - the Green Building Services of the Office for Sustainability) with all new vapor tight super T-8 fixtures and occupancy sensors and is testing some pole mounted LED fixtures on the top deck. The new lights are predicted to save about 40% in energy costs, greatly increasing the percentage of the building powered by the new turbines. The turbines are are expected to produce enough electricity to power six average American homes. A link to a Harvard Gazette article can be found here.

Calculating Energy Savings

On Friday, I presented a brown bag lunch presentation on Calculating Energy Savings to the OFS staff. The presentation started with a look at some spreadsheets I'd created to quickly calculate the savings from two easy energy retrofits... reduced pressure drop air filters and premium efficiency motors. The Excel file had pages started for calculating a number of other types of savings, but wasn't quite ready to share at this time. Next we went over part of the attached Power Point starting with how to calculate lighting fixture requirement using the Lumen Method (the agenda on the second page of the presentation was never changed to represent the actual presentation). We then went over the Fundamental Law of Illumination and how fixture distance affects illuminance. The presentation continued with an explanation of energy models and how they work. We then finished by looking at an eQUEST version 3.62 model for one of the undergraduate houses and quickly reviewing some of the inputs and summary reports. About 6 people attended.

Integrated Design and LEED

On Monday, September 14th, I taught my first full lecture at our ENVR 119, Green Building Design, Construction and Operations class at the Harvard Extension School. The class was well attended (about 40 people in the classroom) and was watched by many more live via the web. For the first time we had an online chat room up so that people could talk to each other during the class and ask questions, which teaching fellow Andrea Ruedy Trimble would read aloud. We know at least one student watched from Brazil and we expect the class from Tsinghua University in China to watch the recorded version. Tsinghua University has partnered with the Extension School to offer our class at their University, watching our lectures and using our assignments, but grading their own papers and supplementing our lectures with their own introductions.

The class on Monday was extended to three hours instead of its usual two hour format. For the first hour, I spoke about Integrated Design. The class asked lots of good questions and we had excellent participation. Rafal Shurma spoke next for one hour about international green building rating systems. It always makes me smile to see BREAM for Prisons as a formal rating system. Finally, I spoke from 9:30 to 10:30 pm about the US Green Building Council's LEED Rating System. I talked about the overall structure of the LEED system and then walked through the specific environmental attributes identified in the 2009 version of LEED for New Construction and Major Renovations. We also announced a study group for students wanting to prepare for the LEED Green Associate examination. A surprisingly high percentage of students stayed in class until 10:30 and about 5 even stuck around to ask questions. Copies of both of my presentations are attached.

LEED for Homes Platinum

Walked by 2 Grant Street the other day. This is Harvard's first LEED for Homes Platinum building. It was a full-gut renovation of a 1,000 square foot house originally built in 1867. The project used a Mitsubishi Heat Recovery Ventilator (HRV) to ventilate the house in an energy efficient manner (pictured). This is a preferred method of ventilation compared to ventilating by leaving the building envelope really leaky (the more common method) and is especially effective in a hot-roof application where insulation is applied directly to the underside of the roof (as was done in 2 Grant). The project uses a high efficiency condensing furnace (95.5% efficient) for heat and air conditioner (13 SEER) for cooling and Icynene spray insulation to improve the envelope performance. Domestic hot water is provided by an instantaneous water heater as needed by the occupants (no storage tank) and all appliances were selected to be Energy Star rated. The team selected all low-emitting materials and otherwise environmentally friendly materials, water efficient fixtures (saving 40%), and carefully designed the project to be durable and avoid mold or moisture damage. This is only the second LEED for Homes Platinum at any university and the fist renovation.