08 / 31 / 2020
If you’ve been following us on any of our social media platforms, you may have heard of the hashtag #lohihipo – short for Lower Highlands High Performance.
Late in 2018 we were commissioned to design a new single-family home, for a young couple who were avid gardeners – seeking to capitalize on Passive House principles, high performance design and great architecture.
We at Bonsai Design + Build stepped up to the challenge. Iteration after iteration, working in conjunction with our clients, we explored various concepts before arriving at the final design. A unique home that was to be first and foremost – High Performing but at the same time contextually appropriate, form simple, programmatically fitting, and of course – gardening enthusiast accommodating!
The specification for the house is to reach Net Zero standards, and because of this, we were able to capitalize on the City of Denver’s, “unofficial” EZ Pass program to obtain building permit approval within a handful of weeks, vs a handful of months as is standard process. (talk to us if you want a quick permit, we have the scoop!)
Net Zero requires that 100% of the homes anticipated energy demand be offset by on site energy production. This automatically precludes the use of gas – as natural gas is not something that can be produced on site, thus – no gas lines were brough on site and the home was designed to be 100% electric. Next, the building envelope needed to be designed to minimize energy loss. For this, Passive House principles were implemented; SIPs or Structurally Insulated Panels were specified to provide the home with an R40 of mostly thermally un-bridged insulation/resistance. This is nearly double of what code requires. Because SIPs are panels, huge chunks of the walls were already “airtight,” and only require taping seams. The 3 ACH, or Air Changes per Hour, that code requires will be easily exceeded. Alpen High-Performance windows were specified. Building fenestrations are where most energy losses are realized in code-built structures. Alpen triple pane windows provide a higher R value, air seal better, and reducing the risk of condensation and mold. The fact that Alpen is a Colorado company and the windows are manufactured locally is icing on the cake!
Because the home is designed to be super airtight with high insulation values, a whole house fresh air circulating system is needed. We specified an Energy Recovery Ventilator (ERV) which will provide the home with continuous fresh air, 100% of the time, while filtering major pollutants and recovering much of the ambient energy from conditioned spaces. The ERV will also recuperate a significant percentage of the conditioned airs moisture and humidity, which we Coloradoans know all to well is important in our dry climate. This only adds to the buildings inhabitants’ comfort which is a key Passive House principle.
The corner lots south west orientation perfectly lent itself to capture the morning suns abundant energy, thus at the main floor a higher window pattern was used to brighten the interior spaces yet maintain a sense of privacy from the adjacent public sidewalks. The structures form steps back along the south and west elevation giving the home a sense of scale while creating plentiful outdoor spaces.
Because of the form factor, two roof decks, one at the 2nd floor and the main deck at the homes roof were created, both engineered to carry heavy loads. Our clients are planning on installing several raised planter beds, making a fully functioning, food producing garden, fit for future trees. Because of the need to bring gardening supplies up and down the various roofs, it was important to keep circulation for this utilitarian and often dirty function to the exterior. The home’s unique façade was born out of necessity to provide an exterior stair dedicated to serving vertical access to the roof decks.
Currently the home is making its way into finishes and we are excited to see this unique and high performing piece of architecture take its place on an auspicious corner in one of Denver’s trendiest neighborhoods, the Lower Highlands!