Home Remodeling Magazine: Energy Stars

March 31, 2017

Below is an article A3's Alison Alessi wrote for Home Remodeling Magazine that provides an outline for energy efficient home renovations. Be sure to visit the Home Remodeling Website and pick up a copy of their magazine for inspiration on your next renovation project!

All photography is by Dan Cutrona.

8 Tips for renovating a home with energy efficiency in mind

There are many advantages to renovating your home, from increasing value to creating a space that fits your lifestyle perfectly. But a less obvious opportunity also exists: the chance to assess and address energy efficiency within the home. When wall and roof cavities are open, it is easier and more cost effective to tighten an older house or fix insulation problems. Add in rebates and tax credits for the energy-efficient updates and homeowners stand to save even more money along with reducing their energy bills and carbon footprint.

While renovation projects can be more challenging to make energy efficient, in comparison to new construction, there are still many opportunities. Consider the following:

1. Start with an energy audit

No matter the scale of the project, start with an energy audit. An energy audit is quite simply an assessment of the mechanicals and insulation levels in your home. Locally, the Cape Light Compact provides comprehensive energy audits with free LED light bulbs. They also fund up to 75% of recommended incentives. There are programs available for commercial, institutional and renters as well as home owners. These incentives are available every year, so even if you’ve had an audit recently, there may be more that you can do.

2. Diagnostic testing during construction can ‘catch’ mistakes

If you are doing a significant renovation or addition, you might also consider HERs rating. Home Energy Rating is required by code for most new construction. We find working with a HERs rater to be invaluable. During design they create energy models to predict energy performance. We typically ‘test’ multiple types of insulation and mechanical strategies. Then, during construction, a HERs rater can diagnose duct and air leakages that are very difficult to find and repair when the home is finished. We have detected many serious leaks during construction that were fixed to save homeowners thousands of dollars in future energy costs.

3. Insulate from the outside!

Another strategy for renovation projects is blown-in insulation: cellulose, which is locally produced using 90% recycled content from newspapers, is the preferred material. It can be blown in from the exterior to make sure all bays are filled with insulation. It can be much neater to attack this problem from the outside. For roofs, adding spray foam insulation can be great for air sealing, especially for more complicated rooflines. If your house has mechanicals in an un-insulated attic or basement, you should consider getting these mechanicals in conditioned or at least insulated spaces. Usually the easiest way to accomplish this is by insulating the sloped roof rafters of the attic or the basement walls.

Scargo Lake Cottage - Energy Star for Homes Renovation

4. Windows can make a big difference

While it’s impractical to reproduce a true divided light historic window, many double-glazed higher performing windows have simulated divided lights and spacer bars and historic profiles that replicate historic windows with higher performance. However, before you consider replacing all windows, blower door test the house and seal the gaps around the window and under the trim. The return on investment for new windows is really high! That being said, new double-glazed windows help with energy loss, cross ventilation, sound mitigation and thermal comfort.

5. Continuous insulation eliminates thermal bridging

A thermal bridge is a gap in insulation. Each stud is a thermal bridge compared to the bay between filled with insulation. Heat is transferred more easily by wooden studs than by insulation. If you are replacing your roof or siding (something we consider a ‘once in a lifetime opportunity’ for most roofing and siding materials), consider adding a continuous exterior layer of insulation under the new siding or roofing. We have done projects with even as little as one inch of rigid insulation on the exterior of the sheathing. This gives a nice tight continuous air barrier and enhances the insulation level of wood-framed houses. The continuous layer helps eliminate thermal bridging for walls and roofs.

Solar Panels By E2 Solar on our Net Zero Scituate House

6. Getting to net-energy zero

A net-energy-zero house is a building that produces as much energy as it uses. This is a very simple definition but it gives quite a bit of leeway for different approaches. Passive house is another energy standard, one of the most rigorous ones in the world. The standard was developed in Germany but is based on building science from the 1960s and 70s passive houses built in North America. The basic principal is to insulate a house enough so the mechanical load is dramatically reduced. In our climate zone, to achieve near net-zero or near-Passive house standards, insulation levels would have to be R:40 walls, R:60 roof, triple-glazed windows, R:20 basement wall and R:10 under slab foundations. While this certainly requires an initial cost for upgraded insulation, and a serious strategy about where and how to accommodate this additional insulation, the upgrade comes with a significantly reduced mechanical load and monthly energy costs. In many cases, the heating could be as simple as one mini split heat pump. The final piece to achieve net-zero is adding renewable energy, typically photovoltaic panels that produce electricity.

8. Heating with electricity makes sense!?

Many Cape residents no longer or never had access to natural gas for heating. We can’t make natural gas on our roofs, but we can make electricity by utilizing solar photovoltaic panels. If we are serious about getting to net-zero, it’s important to heat/cool/heat water with electricity. Fortunately, there are great options for heating these days. We use mini-split heat pumps for heating and cooling as well as heating hot water for most projects. They are two-to-three times more efficient than the electric resistance baseboard heating of the 1970s and 80s. There are options for ducted and ductless units.

9. Ventilation is VERY important

Finally, a note about ventilation. The first question we often get is “Don’t you want the house to breathe?” Yes, of course we do. However, we want to control that. We don’t want the house to breathe through walls and windows. If you add insulation and don’t consider ventilation there can be problems. We want ventilation – whether from a simple exhaust-only Panasonic bathroom fan or a more sophisticated intake/exhaust whole-house ventilation system that controls how the house exchanges air. Old houses breathe, but new energy-efficient house do too. They do it in a smarter more efficient way.

About the author:

Alison Alessi is a architect with A3 Architects, Inc. in Dennis MA. She is a Certified passive house designer and is passionate about creating low-energy projects for the Cape and Islands and beyond.

ADDITIONAL RESOURCES:

http://energy.gov/eere/energybasics/articles/air-source-heat-pump-basics

http://www.phius.org/
http://selfreliancefuelcoop.org/

http://energycodehelp.com/

http://www.capelightcompact.org/

http://www.masssave.com/

Brewster Flats Blower Door Test

March 24, 2017

Blower Door Test at Brewster Flats House by Home Energy Raters

After insulation is complete we typically test houses for air tightness. This is done by a blower door test. The required tightness by code is 3 ACH (or air changes per hour). We are typically targeting around 1 ACH. During this test, we typically find several “weak links” in the envelope. Often one can feel the draft around windows, at the plate or around masonry fireplaces.

Our HERs rater is locally based in Sagamore Beach Home Energy Raters. http://energycodehelp.com/

They are a 3rd party meaning they aren’t connected to the builder or architect and therefore have an independent role in evaluating the tightness of the house. They provide us with a final HERs certificate required by building code, effectively proving the home is in compliance with the current energy code.

In addition to testing air tightness, the HERs rater typically tests duct tightness. They also provide an independent visual inspection of insulation and mechanical systems. After their feedback we typically tighten up a few areas and have them test again at the final inspection.

Area of Conditioned Space: 3,437 ft2
Volume of Conditioned Space: 35,233 ft3
Loss: CFM at 50pascals
ACH 1 1/2*

*This test was done after insulation, but before drywall was installed. We found some areas that needed additional insulation and air sealing. The contractor will address these areas and another blower door test will be performed when the house is near completion. We expect the final test to be around 1 ACH.

Why Net Zero

March 10, 2017

What is net-zero?

The definition is simple. It’s a structure the produces as much energy as it uses. However, there is definitely more than one way to get there.

Why net zero?

Buildings contribute 30% of greenhouse gases towards global warming and it’s not necessary. We CAN do better. Energy efficiency is the simplest and most effective way to combat global warming.

We love the pristine environment of Cape Cod that we live and work in. We want to set an example of what can be done through design to create construction that is in harmony with its surroundings. Cape Cod is ground zero for climate coastal sea rising and we think it’s imperative to act.

Also, it makes financial sense! An initial investment of slightly higher construction costs – 10% or even much less, can result in no energy bills! That means once you’ve completed construction the annual energy usage would be offset by annual energy production. This is powerful stuff!

A3 Architects we have specialized in energy efficiency and high performance thermal envelopes. We design these net-energy zero homes on a variety of budgets and work with many available incentives. There are several basic strategies for getting to net-zero.

HOW TO GET THERE?

1. “THE NOT SO BIG HOUSE” –FLEXIBLE BUT KEEP THE DESIGN SMALL

The most important ‘green’ thing you can do with a new house is to make it smaller! Susana Susanka’s “Not so Big House’ resonates with our design philosophy. We ask clients to not design their Cape house for the Fourth of July when extended family & guests are here but to design their house how they live most of the year with the idea of designing flexibility into the spaces. So this means, you don’t make a dining room that accommodates a table for 20 guests, but think hard about an open living/dining space that is room for 4 to dine most nights but can be expanded for larger dinner parties. This is important!

http://www.notsobighouse.com/

2. USE ENERGY MODELING

No matter the scale of the project, start with an energy model. WE use energy model as early as conceptual design to understand how siting, glazing and wall thickness affect performance. In the early stages of design we can try multiple wall, roof, foundation and window insulation levels. This gives us the confidence early in the process that the design will approach net-zero.

3. SITING IS IMPORTANT!

If possible south facing glazing, and roof make passive solar and future active solar feasible. If there are major views to the north, or other restrictions on this we can design around it. But, there is no substitute for thinking about the suns path as it relates to your home. We naturally crave light, particularly in the long dark months on winter. And orienting living spaces towards the south can make a dramatic difference in comfort level with natural lighting. Furthermore, south facing roof is required for solar panels that are part of the big picture – energy production.

4. INSULATE, INSULATE, INSULATE!

Insulation is one of the least expensive building materials. Doubling the insulation budget is not going to double construction costs. Infact, although it requires some thoughtful detailing, super-insulation can be achieved in many ways. In general terms we aim for R:10 under slabs, R:20 below grade walls, R:40 walls and R:60 roofs. Most of these numbers are twice what’s required by code. This extra insulation can be placed inside or outside the structural wall depending on the situation.

5. WINDOWS CAN MAKE A BIG DIFFERENCE

Once you’ve decided to add that extra insulation you’ll notice that double glazed windows might not make much sense. There are some exciting triple glazed European windows available that have higher R:values than most homes! This can make a big difference at night when standing by a window in the winter. We pay attention to window details like u;value and solar heat gain coefficient to make sure that the windows are working to help heat the home in the winter.

6. DIAGNOSTIC TESTING DURING CONSTRUCTION CAN ‘CATCH’ MISTAKES

We rely on testing during construction. We test airtightness before insulation, after insulation and at the final occupancy. Airtightness is a measure of how ‘leaky’ a house is. We want to build the tightest house practical. This way we know that are minimal leaks in the exterior envelope for air and water movement.

7. VENTILATION IS VERY IMPORTANT!

The first question we often get is “Don’t you want the house to breathe?” Yes, of course we do. However, we want to control that. We don’t want the house to breathe through walls and windows. If you add insulation and don’t consider ventilation there can be problems. We want ventilation – whether from a simple exhaust-only bathroom fan or a more sophisticated intake/exhaust whole-house ventilation system that controls how the house exchanges air. Old houses breathe, but new energy-efficient house do too. They do it in a smarter more efficient way.