What is it? How do we get there? And why?
And what about Net Positive?
Having worked on many Net Zero Energy (NZE)/Positive projects I realize there are often questions about it. Here is an overview …
Two reasons: it is the right thing to do and because we have have to. Eat your veggies kids, be healthy.
You may not know that California already has a plan to make all new residential projects Net Zero by 2020 and non residential NZE by 2030. Local jurisdictions are acting sooner. Santa Monica just passed a Net Zero requirement starting in 2017. It’s here. The doctor is telling you to get some exercise and the scale doesn’t lie…time to lose weight.
What is it?
Net Zero means a very efficient building with on-site renewable energy generation that in sum creates at least as much energy as it uses in a year (Net Zero) or more (Net Positive).
Simple answer: Efficiency is the first and most critical step – then Renewables.
Design a great building and add some renewable energy side dishes and seasoning, don’t create a pig and feed it over-sized portions of expensive energy (whether made by you or the utility).
Details: for you geeks and people who count their steps …
Renewable energy sources on a building or site (photo-voltaic solar panels, wind turbines, ground source heat pump systems, etc.) are far more expensive than making the building more efficient in the first place. And production of renewable systems has its own environmental impacts, so the less of them needed the better.
An efficient building starts with the envelope (the perimeter cladding or skin). This means: properly designed floor, wall and roof assemblies, sealed tight with adequate insulation, with thermal breaks to reduce heat transfer, high performance window frames and glazing, appropriate building massing, orientation and the proper location and size of openings.
Next comes the heating (and cooling if needed) system(s). First, implement all possible passive strategies including capturing solar heat gain and natural ventilation (operable windows). I am a huge fan of passive strategies first. Then for the mechanical systems the trend is towards highly efficient, all electric powered, heating/cooling sources using highly effective delivery methods. This typically means an air to air heat pump driven system that uses various heat exchange techniques in combination with a radiant delivery system. Such a system can allow heat from the sunny side of a building to be transferred via radiant hydronic (water based) piping to the cold side (or vice versa) before the heat pump or renewables are needed. Radiant tubing, often in the floor, puts heat where you want it, close to occupants.
Finally, review internal occupant and process loads to look for further efficiencies and allow for their impact. A commercial kitchen is highly energy intensive for example, but there are tools to mitigate impacts such a equipment selection and menu design (no fries kiddies). Lighting efficiency and control systems have been vastly improved with new LED technology and sensor technologies.
A Win Win
In addition to lowered operation costs on businesses, NZE is creates new business opportunities and jobs.
Do it, you’ll feel better. And live longer.