Spartan Architectural Design
An affordable Zero Energy Home begins with an integrated Zero Energy Home (ZEH) design that offers our clients the ability to view the home and construction details of the home-BEFORE THEY BUY IT!!!!
Spartan believes It is best to develop a ZEH design in conjunction with a project team – owner, builder, energy consultant, the landscaper, and designer. Getting to the level of insulation, air tightness, energy efficiency, and solar exposure needed to create a cost-effective Zero Energy Home requires that a wide variety of small issues be effectively addressed in the design phase, including exploring the most cost effective options for reaching Net Zero and verifying them through Revit / AutoCAD Energy Modeling.
The Building Site
For the most cost-effective ZEH design, the selection of the site and the location of the home must consider climate, weather patterns, wind, sun exposure, shade, temperature, heating/cooling degree-days and topography. It is important to choose a site with a sufficiently wide east-west lot line to allow for the placement of the home on the site so that there is adequate south facing roof for solar collectors and south facing windows and doors for passive solar gain. The site should be free of immovable obstructions, such as trees, neighboring homes, and land-forms that could interfere with adequate solar access.
A thorough solar evaluation of the site, using automated shade analysis tools, will be conducted by Spartan. The Analysis and Reports, provide details on shade and solar access for the home and offers digital and graphical displays of the amount of solar energy available at the site.
The solar analysis is important for designing passive solar, solar photovoltaic (PV) and solar thermal (hot water) systems. It impacts the site selection, location and orientation of the home and roof, roof design, and roof and window area needed for solar PV and passive solar. This data may also indicate which trees need to be cleared or trimmed to increase solar exposure.
Zero Energy Homes should be designed to use the sun’s energy as much as possible, for: generating electricity, heating hot water, and utilizing passive solar space heating. After a site analysis and an understanding of what solar resources are available on site, passive solar design concepts should be incorporated.
LEED Design Points
After the site and solar analysis has been concluded, the next step is for the Spartan Building Scientists to assist with identifying and defining the LEED project parameters and specifications and for Spartan to complete the home design to achieve LEED points and ratings as per building owners goals and budget directives. This document acts as the “road map” for the project. The B.O.D. identifies key project elements such as homeowners’ requirements and preferences; building type, scope, and key design details; specific goals, strategies, and specifications for reaching Zero Net Energy; and the LEED goals and objectives.
Size and Shape Matter
Spartan will review with building owners, the design and the construction options, of an affordable Zero Energy Home, size and shape do make a difference on cost implications. Smaller homes use less energy for space heating and cooling. Limiting the size of the home will have a direct impact on overall energy usage, helping to reduce costs. The savings from building a 10% smaller home can help pay for the additional cost of a Zero Energy Home without sacrificing quality. Smaller homes can be designed to look, feel, and live larger while also having ample storage space, and can be more convenient and livable than larger homes.
Shape is also important. The shape of the home should be kept simple and in scale to the user and the site. Rather than a sprawling design, a building with a low exterior surface to volume ratio, with simple clean lines and minimal “corners” will save energy and construction costs. It is useful to think of the home as an insulated six-sided box with the insulated floor, four walls, and ceiling making up the “box”. Each additional corner or cantilever increases the amount of framing required and makes air sealing and insulating more challenging.
Solid Core SIP Panel Buildings
Think of the home as a six-sided box in which all six sides need to have the most cost-effective insulation possible. Think of a beer cooler, the closer the results to building a beer cooler, the better. The R-values on each side of the box, as determined by energy modeling, must be sufficient to reach the zero net energy goals.
SIP Panels provide maximum results with thicker insulated walls, super-efficient floor and roof, provide the best home insulation materials and methods to achieve ZEH goals and objectives. SIPS provide a continuous air barrier. All the cracks, holes, and exterior envelope penetrations of a normal sick built home are problematic. A SIP building is systematically sealed on all sides. All penetrations, for electrical, HVAC, venting, gas, and water are minimized and included in the design.
Internal HVAC Ducts
All duct-work is designed to be within the conditioned space to optimize the integrity of the air barrier and insulation. According to Green Energy Advisory, ducts can be kept inside by locating them in conditioned areas such as crawl space, un-vented conditioned attic, open-web floor trusses (especially in a two story home), soffits, dropped ceilings, or a chase designed into special roof trusses.
SIPS Minimize Thermal Bridging
With SIP Buildings, thermal bridging is eliminated, from foundations, edges, corners, soffits, eaves, connections, decks and penetrations. Door and window cut outs are precise, and allow for quick easy window and door installations.
The orientation of doors and windows must take climate, wind, sun and shade into account. Since the home is a well-insulated, highly airtight, “six-sided box,” windows and doors must be installed properly, and minimizing window area is a very important design strategy for achieving an affordable Zero Net Energy Home. Minimizing window area, while providing plenty of light, optimal passive solar heating to living areas, and adequate ventilation in the summer presents a unique design challenge.
An overall window to floor ratio of about 14% and, in northern climates, a south facing window to floor ratio of 6%, are often recommended for a Zero Energy Home, but that ratio will depend on the climate, as well as site and design considerations. Low U-value windows are important (from U 0.14 to U 0.23 as needed to reduce heat loss and maintain optimum comfort), but are less effective as the window area increases. South-facing windows should have a Solar Heat Gain Coefficient (SHGC) of o.5 or greater, in conjunction with climate appropriate overhangs, to allow for passive solar heat gain in the winter months, but not in the summer months. Fewer larger windows are more energy efficient than more, smaller windows, because there is a higher glass-to-frame ratio with larger windows, and the frames are where the leakage occurs because the frames have a lower u-value than the glass area of the window. Casement and fixed windows are less leaky than sliders or hung windows.
Heating, Cooling, Ventilation and Hot Water
If heat-pump ductless mini-splits are used for heating and cooling, airflow to all the rooms needs to be considered during the design phase. Utilizing door cuts under the bedroom doors, transoms over some of the doors, or sound insulated air vents in the walls could be part of the design. Preferably, energy efficient ventilation systems (ERVs and HRVs) may be used to optimize airflow in the home. Specifying models of ERV/HRVs that have a circulation mode that actively circulates air from the heat source in the living area to the bedrooms can bring both heat and cool air to all rooms without needing any additional venting, and ensures that the heating requirements of the building code are met. In cold climates, heat-pump mini-splits that provide heat down to minus 18 degrees below zero should be specified, such as the Mitsubishi “Hyper Heat” model. Care should be taken that the heating system is sized properly for the local climate and home dimensions and characteristics. For greater efficiency the HRV/ERV needs to be centrally located so that it has short runs for supplying air to the living area and bedrooms and for extracting air from the kitchen and bathrooms. The location of the HRV/ERV should be part of the design and should be designed to accommodate the specific model chosen, as size varies considerably.
The hot water tank needs to be centrally placed to bathrooms and kitchen to minimize hot water runs, or consider a half-loop hot water recirculation system. Energy modeling should be conducted to determine which hot water system is most cost effective: Solar Thermal, Heat Pump Hot Water Tanks, or a well-insulated standard electric water heater with electricity supplied with additional solar panels. Once the most cost effective hot water system has been determined, the design needs to include adequate space for the system selected.
Final Architectural Designs
Spartan’s main goals for clients are delivered in the achievement or near achievement of a Zero Energy Home. Spartan realizes that there are affordable Zero Energy Homes, but these should match building owner’s budgets as compared to the LEED designs objectives. Spartan uses standard building techniques combined with advanced 3D Models, and Architectural visualizations that define all aspects of building.