Design considerations


 

Size and shape 

From an energy perspective, simple, compact shapes perform better. For example, a sphere will give the best energy performance and in the world of right angles a cube is best. The idea is to minimize the surface (where heat is lost) while maximizing the volume of your living space. The less compact the building shape, the more insulation will be needed to compensate. Any nooks and crannies and protrusions like dormers will hurt your energy performance and add to construction costs. Also, corners are particularly challenging to seal and insulate well. The more corners and protrusions you have the harder it is to achieve a good, tight envelope. Current tastes in architecture tend toward complex surfaces but there are many ways to provide visually appealing exteriors while still using a simple building envelope shape. For example decks, exterior walls, and porches can provide the appearance of depth and texture.

In designing a high-performance house, the whole house is considered as a system. The integrity of the thermal boundary is of the utmost importance and the heating and ventilation systems are carefully sized so that everything works together to create a healthy and comfortable house.

Remodels 

Homes can be remodeled to Passive House standards. It can be difficult, depending on the configuration of the house, but it isn't impossible. In Europe retrofits are often done using Passive House techniques but without the expectation of being certified. Instead of reaching the Passive House standard of 15 kwh/sq meter, they might be able to achieve 25 kwh/sq meter instead - still a very energy efficient and admirable achievement.

Techniques to achieve energy efficiency in Passive Houses include making them as airtight as possible, using lots of insulation, using heat recovery ventilation as part of the HVAC system, optimizing passive solar heat gains, and the use of very high efficiency windows and doors. Each piece is an important part of the whole interactive system of a properly functioning house.

We would assess your current construction and come up with a retrofit plan using the very accurate Passive House modeling program, PHPP. With PHPP we can readily see the effect of different possible retrofit measures so that we can choose the best path to meet your goals within your budget. Throughout the process we would work closely with you, your architect and your contractors.

The earlier the energy considerations are integrated into the planning process, the more effective and affordable they will be. Piggy-backing on structural and other repairs, the overall cost of home performance improvements will be reduced.

 

 



 

The two figures above are pages out of the Passive House Planning Package (PHPP) software. With it we can make detailed energy models showing the effects of building component changes.