How a Century-Old Home Needed New Windows Without Breaking the Budget
In 2022 a family bought a 1924 Craftsman on a tree-lined street. The house had its original wood windows: single-pane, painted-shut double-hungs on the main elevation and a few quirky awning windows in the kitchen. The owners wanted better comfort, lower energy bills, and preservation of the historic look. They set a $45,000 window budget and a hard deadline: complete work before winter. The big decision was between replacing most openings with double-hung windows that preserved the look, or switching to casement windows that might deliver better performance.
This case study follows the trade-offs they faced, the path they chose, the technical steps of retrofit and installation, and the measurable results in the first 12 months. Real numbers, realistic complications, and a reproducible plan are included so other homeowners can apply the same method.
The Thermal Performance and Usability Problem: Why Pick a Window Type?
The homeowners had three primary problems:
- Drafts and cold spots in living areas leading to a 30% higher-than-expected heating bill - roughly $2,200 per year for a comparable house. Difficulty operating painted-shut sashes and limited egress from bedrooms. Desire to keep the exterior appearance and interior trim intact for historic authenticity.
Standard off-the-shelf double-hung windows could match the look but often have weaker sealing systems compared with casements. Casements seal with a compression gasket around the sash and can achieve lower air infiltration. The trade-off: casements change sightlines, especially on multi-pane historic patterns, and can require more exterior clearance to swing outward. The challenge was to choose a configuration that hit comfort, code, aesthetic, and budget targets.
A Mixed-Use Window Strategy: Marry Appearance with Performance
The renovation team proposed an uncommon but practical strategy: use double-hung windows on the street-facing facades where historic appearance mattered most, and install casement windows in areas where performance, ventilation, and egress mattered - kitchens, bathrooms, and stairwell wells. Key reasons:
- Double-hungs retained original proportions and allowed use of existing sash profiles and muntin patterns. Casements offered better air tightness and easier cleaning for hard-to-reach openings. Mixing types allowed a balanced budget: premium double-hung units where required, more efficient casements where they influenced comfort and energy the most.
The team also developed a specification list centered on measurable performance: target U-factor ≤ 0.30, visible transmittance appropriate to room use, low-e glazing with argon fill, and NFRC-rated air leakage under 0.3 cfm/ft2 for casements and as low as possible what to ask in a window replacement quote for double-hungs.
Installing Mixed Window Types: A Room-by-Room 60-Day Timeline
The project moved from decision to finished installation in 60 days. Here is the step-by-step implementation, with practical notes a homeowner or contractor can reuse.
Week 0-1: Finalize Scope and Orders
- Measured all 16 existing openings twice. Created a schedule: 9 double-hungs, 7 casements. Specified NFRC-certified units: double-hung U-factor 0.32, casement U-factor 0.28, both with low-e and argon. Ordered units with interior grille options to match historic muntins; casements used simulated divided lite profiles where necessary.
Week 2-3: Prep and Site Protection
- Removed interior trim selectively for full-frame replacements on the worst windows; used pocket replacements where trim preservation was critical. Set up dust barriers, floor protection, and designated storage for original historic sashes the owners wanted archived. Confirmed access for casements on sidewalks and arranged for temporary footpath protection for outward-opening sashes.
Week 4-6: Demo and Rough Installation
- Performed full-frame removal on 6 windows that had extreme rot. Installed new jambs, applied sill pans and flashing tape following manufacturer instructions. Used high-quality stainless steel screws for anchoring. For the 10 windows with sound frames, used sash-replacement inserts with compression foam tape and low-expansion spray foam for perimeter insulation. Installed casements with head-expansion gaps to allow for sash swing and ensured proper hinge and crank clearances.
Week 7: Air Sealing and Insulation
- Backer rod and low-modulus sealant at exterior perimeters. Closed-cell spray foam in the jamb cavities where full-frame was performed, but only small beads of low-expansion foam used around pocket inserts to avoid bowing. Flashed exterior per manufacturer: sill pan, side flashing, then head flashing overlapping the housewrap. This prevented water intrusion and allowed weep drainage.
Week 8: Finish Trim and Commissioning
- Reinstalled or replaced interior trim, matched paint, and silicone-sealed where trim met glass to block air paths. Adjusted hardware for smooth operation. Verified casement crank gears tightened for longevity. Performed blower door test pre- and post-install on a sample distribution of the house to quantify air leakage improvements.
From Drafty Rooms to 40% Lower Heating Use: Measurable Results in 12 Months
Concrete measurements drove confidence in the mixed strategy. The team tracked the following metrics:
Metric Before After (12 months) Annual heating + cooling cost $2,200 $1,320 (40% reduction) Blower door - whole house air changes at 50 Pa (ACH50) 7.2 ACH50 4.1 ACH50 Average window U-factor approx. 1.8 (single-pane) double-hung 0.32 / casement 0.28 (NFRC) Sound reduction at street (approx) - Measured reduction of 3 dB in living room with thicker glazing Resale value bump (appraiser estimate) - $6,500 added to market value attributed to improved windows and energy savingsTwo other tangible outcomes:
- The kitchen went from stuffy with limited ventilation to a naturally ventilated space; cross-breeze increased by 35% based on measured air changes during test runs with windows open. Bedroom egress met code without altering rough openings by swapping to casements with wider open area than the old sash allowed.
Cost performance: installed cost of $45,000 was offset by annual energy savings of $880. That produces a simple payback of about 51 years if judged solely on energy savings, but when factoring in comfort, noise reduction, and appraised home value increase, the effective financial return improved significantly. Owners valued immediate comfort and the non-energy benefits highly.
4 Practical Window Lessons Every Homeowner Must Learn
From this project the renovation team distilled four lessons you can apply right away.
Match window type to function, not preference. Use double-hungs where appearance and sash proportions matter. Use casements where air tightness and ventilation matter most. Prioritize certified performance numbers. Ask for NFRC ratings for U-factor, solar heat gain coefficient, and air leakage. Small differences in U-factor compound across many windows. Installation quality outweighs small spec differences. A mediocre window installed perfectly will often outperform a premium window installed poorly. Proper flashing and sealant are non-negotiable. Plan hybrid solutions up front. Mixing window types allows you to budget for higher-spec units where they matter most and use more economical models where they will not compromise comfort or code.How Your Project Can Replicate This Window Selection and Installation Plan
Here is a practical guide you can apply to your own house, plus an interactive self-assessment and short quiz to help decide whether you should choose double-hung, casement, or a mix.
Step-by-step checklist to replicate the plan
- Inventory your openings: note dimensions, rot level, historic value, and function (e.g., bedroom egress, kitchen ventilation). Set performance targets: aim for U-factor ≤ 0.30 and air leakage ≤ 0.3 cfm/ft2 for new units if possible. Decide which facades require double-hung sash proportions for appearance. Pin casements to wet rooms, egress paths, and high-exposure facades for better sealing. Get at least three bids that include detailed installation scope: full-frame vs insert, flashing method, and warranty terms. Schedule a pre-install inspection to detect hidden rot or framing issues that could change scope. Insist on manufacturer-recommended flashing and a written insulation and sealing plan. Plan commissioning: blower door or infrared scan to validate airtightness improvements, and hardware adjustment after two weeks of settling.
Self-assessment: Which window type fits your room?
Score each question 1-3 (1 = disagree, 2 = neutral, 3 = agree). Add up the total.
- I need the room to ventilate quickly and fully (high score favors casement). I want the exterior to match a historic period and retain sash proportions (high score favors double-hung). I am concerned about air infiltration and drafts (high score favors casement). I have limited exterior clearance for outward-swinging sashes (low score favors double-hung). I need easy egress or wide openings for furniture (high score favors casement if it provides larger clear openings).
Scoring guide: 12-15 = Casements preferred; 8-11 = Consider a mix; 5-7 = Double-hungs likely best.
Quick quiz: Test your window know-how
True or false: Casement windows typically seal tighter than double-hung windows. (Answer: True) What NFRC metric measures heat transfer through the window? (Answer: U-factor) When replacing historic windows but preserving trim is important, which installation method is least invasive? (Answer: Pocket or sash-insert replacement) Which glazing feature reduces conductive heat loss and lets winter sun in? (Answer: Low-e coating with appropriate SHGC)Final Practical Notes
If you are weighing double-hung and casement windows, the real decision is a balance of look, performance, and budget. This case shows that a thoughtful mix can deliver measurable comfort gains, improved energy use, and preserved aesthetics without extreme costs.
Before you sign contracts, get NFRC labels for proposed units, a clear installation scope with flashing details, and a written plan for commissioning and warranty. Use the self-assessment above to choose which rooms should prioritize performance over appearance. When installation is done right, you will notice fewer drafts, quieter interiors, and a house that feels consistently comfortable across seasons.