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Day 2 of the Buildings XVI Conference hosted by ASHRAE and Oak Ridge National Laboratories in Clearwater, Fla., was another day of fascinating building science discussion and education.
Photo: Fabio Oggero, Paolo Mazzo – amazingarchitecture.com
Upgrading a national treasure
Stefano Fantucci from the Italian Department of Energy presented a remarkable case study revealing a number of innovative and creative approaches used to renovate a heritage building in Italy to today’s energy efficiency codes. The building in question is one of the executive villas built by the Olivetti company in the 1930s as part of its purpose-built industrial town of Ivrea, in the Piedmont region, which is now a UNESCO world heritage site. The founder, Camillio Olivetti, was attempting to bring U.S. manufacturing concepts to Italy and borrowed many American architectural styles for the factories, offices and residences he constructed. Villa Rossi was made in a flat-roofed modernist style and could not be esthetically altered on the exterior or interior. The walls were brick exterior and interior with a simple air gap in between. To insulate them, Fantucci’s team filled the air gap with recycled cork chips, taking them from an R5 to an R18 insulating value. The window frames could not be altered, so they installed cork board behind them to act as a thermal break. To insulate the radiators, they installed an aerogel blanket and reflective foil on the wall behind them. The windows were Wagner system – an early Nordic precursor to double-pane windows where two framed single-pane windows are combined in a single casement. To make them more energy efficient, Fantucci simply had the glass replaced with a low-E hard coat on the interior surface, improving the U-value and still allowing for cleaning of the glass. The owners would not allow an air conditioning system to be installed, so the team painted the roof white and installed PCM board in the ceiling. The house is ventilated by no fewer than 27 small chimneys on the roof that were open to the interior. The renovators designed and installed flues that enabled the chimneys to open and close with changes in temperature, and installed a number of other ventilation shafts that draw cool air from the basement to the upper levels of the house. The result? Wall U-value improved by 70 percent, window heat loss dropped 32 percent and the roof U-value improved by half.
Getting all the way off the grid
Matt Domsy of Carleton University presented his case study of a solar-powered Passive House home in Ontario’s Bruce Pennisula that the owner wanted upgraded to use no fossil fuels at all. The home was producing 25 megawatts per year from its solar panels but only needing five megawatts for all its functions. But the its battery storage system was not sufficient to cover the heating needs in winter, so the owner still needed propane heat as a backup. The owner installed a massive 50,000-liter water tank as a heat sink connected to a heat exchanger, an air/water heat pump, an electric boiler and a secondary water tank to act as a diurnal heat sink connected to a hydronic home heat system. Once they got it all working, they found the solar panels could charge the storage tank with enough hot (50-degree) water to supply the hydronics for the entire winter.
Trowel-on insulation
Ali Naman Karim of Chalmers University in Sweden showed his research into aerogel-coated mortar. ACM is a coating mortar with the sand replaced by aerogel particles – a substance with an extremely low thermal conductivity. The coating has to go on quite a bit thicker than regular coating mortar – 50 millimeters versus 10 – and takes an additional four months to completely dry. But it cuts heat transfer through the wall by about half. Karim suggested it could be a good solution for heritage renovations where adding regular insulation is not an option and the cost is less of an issue.
Bright days, dark nights
Wahid Maref of the University of Quebec talked about research into whether solid state phase change material (SSPCM) coatings on windows behaved differently depending on building orientation. These are the materials that are used to to create dynamic glass that can change opacity in response to electric current or heat. They absorb heat and block its transmission even more than low-E coatings and are therefore useful for enhancing the insulating value of windows. However, they are not as transparent as low-E and affect the opacity of the glass. They also change opacity as they are heated, becoming transparent in high sunlight and clouding as the window cools. Maref and friends found a 8.2 percent reduction in winter heating loads in the spaces where the SSPCM was used. The study was done in Montreal and the north- and west-facing windows stayed transparent longer on sunny days. On cloudy winter days, the windows sometimes did not clear at all. Maref suggested the technology might be useful in commercial applications where the building is only used during daytime work hours.
A moisture mystery
Researchers are working on the problem of how to predict the insulating value of biologial materials such as wood chips and straw. Sustainable builders want to use them because they make use of materials that would otherwise be waste; are potentially very cost-effective; and can be highly insulating. The problem is, their moisture content is very high and fluctuates with temperature changes, which changes their insulating value. Oskar Ranefjard of Lund University has made some progress modeling the behaviour of wood fibre, hemp and cellulose, showing how it releases heat as it absorbs moisture and collects heat as it drys through a process called hysteresis. This could be useful in cold climates with big day/night temperature fluctuations, as the insulation would gather heat during the day then slowly release it through the night as humidity in the wall cavity increases.
Attic design tool
David Yarborough of R&D Services explained a modelling tool he helped develop that calculates heat flows in attics in response to multiple inputs. Yarborough explained the complex problem of understanding conduction, convection and radiation through an attic cavity, but feels his model solves the necessary energy, momentum, surface-to-surface and surface-to-ambient radiation equations. Users can input variables for air properties, temperature, emittance of surfaces, dimensions of the space and direction of heat flow to generate heat flow diagrams and R-values.