Week 3

This week we began to work on the calculations and design for our library's envelope. We began this process by calculating how much energy per year we can use for heating based on PassivHaus standards. These standards specify that 15 kWh/m^2 can be used per year for heating and cooling and we decided to allocate 10 of these kWh/m^2 to heating leaving 5 for cooling. We found our total floor area to be 574 m^2 and so we can use 5740 kWh or 2.0664E+10 J for heating per year. Then, continuing to work backwards we found that the average Heating Degree Days (HDD) for our area is approximately 2600 KDays or 2.264E+8 KSeconds. The next step for our calculations is to choose a heating system for our library which we cannot actually do until we complete our site assessment and receive feedback from Dr. Patricia Gallagher, a geotechnical engineering professor who we emailed for input, so for now we will use an estimated efficiency of 3 for our geothermal heating system. Next we must calculate our max K-tot, the building heat loss transmission coefficient by multiplying the total energy use for heating per year by the heating system efficiency and dividing that value by our HDD in KSeconds. This yields a value of max K-tot = 2.7596E+02 W/K. Next we must choose the materials to use in our envelope based on their R-values in order to keep our actual K-tot below our calculated max K-tot which we will continue to work on throughout this week.